Tax

6 operations in the Tolvi API, version 1. Paths are relative to https://api.tolvi.co.uk. Every amount is integer pence.

Get the corporation tax computation

GET/api/v1/engagements/{id}/tax

Scopes: engagements:read

From the final TB via @tolvi/tax-engine, with deferred tax on fixed assets. Part of the working_papers product: the firm must have it and you must have access to it.

Parameters

Parameters for GET /api/v1/engagements/{id}/tax
Name	In	Type	Description
`id`required	path	`string (uuid)`	Engagement id.

Responses

200 OK, `application/json`

Body: object (TaxComputation).

200 OK response for GET /api/v1/engagements/{id}/tax
Field	Type	Description
`applies`required	`boolean`	Corporation tax applies (companies only).
`error`required	`string`nullable
`inputs`required	`object (TaxInputs)`	Tax inputs the TB cannot give. Capital allowances are not among them: they come from the fixed asset register (C).
`inputs.associatedCompanies`required	`integer`	0 to 1000
`inputs.aiaPence`required	`integer`nullable	Integer pence (GBP). Deprecated: capital allowances come from the fixed asset register (section C, /fixed-assets). Echoes the register’s figure. AIA claimed. deprecated
`inputs.mainPoolBfPence`required	`integer`	Integer pence (GBP). Deprecated: capital allowances come from the fixed asset register (section C, /fixed-assets). Echoes the register’s figure. Main pool WDV b/f. at least 0; deprecated
`inputs.specialRatePoolBfPence`required	`integer`	Integer pence (GBP). Deprecated: capital allowances come from the fixed asset register (section C, /fixed-assets). Echoes the register’s figure. Special rate pool WDV b/f. at least 0; deprecated
`inputs.disposalProceedsPence`required	`integer`	Integer pence (GBP). Deprecated: capital allowances come from the fixed asset register (section C, /fixed-assets). Echoes the register’s figure. Disposal values deducted from the pools. at least 0; deprecated
`inputs.otherAdjustments`required	`array of TaxAdjustmentInput`	up to 100 items
`inputs.otherAdjustments[].description`required	`string`	up to 200 characters
`inputs.otherAdjustments[].amountPence`required	`integer`	Integer pence (GBP). Positive adds back, negative deducts.
`inputs.lossesBroughtForward`	`object (LossesBroughtForward)`	Last year’s losses carried forward (set by the roll forward). Absent: none.
`inputs.lossesBroughtForward.pre2017Pence`required	`integer`	Integer pence (GBP). at least 0
`inputs.lossesBroughtForward.post2017Pence`required	`integer`	Integer pence (GBP). at least 0
`profitBeforeTaxPence`required	`integer`	Integer pence (GBP).
`adjustments`required	`array of TaxAdjustmentLine`
`adjustments[].description`required	`string`
`adjustments[].amountPence`required	`integer`	Integer pence (GBP).
`adjustments[].reference`required	`string`	Legislation or HMRC manual reference.
`additionsPence`required	`integer`	Integer pence (GBP).
`aiaPence`required	`integer`	Integer pence (GBP).
`mainPoolPence`required	`integer`	Integer pence (GBP).
`mainPoolWdaPence`required	`integer`	Integer pence (GBP).
`specialRatePoolWdaPence`required	`integer`	Integer pence (GBP).
`balancingChargePence`required	`integer`	Integer pence (GBP).
`capitalAllowancesPence`required	`integer`	Integer pence (GBP). Allowances before balancing charges, from the fixed asset register (C).
`fixedAssetRegister`required	`boolean`	Section C has a fixed asset register; without one no allowances are claimed.
`mainPoolBfPence`required	`integer`	Integer pence (GBP).
`specialRatePoolBfPence`required	`integer`	Integer pence (GBP).
`disposalValuesPence`required	`integer`	Integer pence (GBP).
`firstYearAllowancesPence`required	`integer`	Integer pence (GBP). Full expensing, special rate allowance and other first-year allowances.
`otherAllowancesPence`required	`integer`	Integer pence (GBP). Single-asset pools, SBA and balancing allowances.
`mainPoolCfPence`required	`integer`	Integer pence (GBP).
`specialRatePoolCfPence`required	`integer`	Integer pence (GBP).
`lossesBfPence`required	`integer`	Integer pence (GBP). Trading losses brought forward (both regimes).
`lossesUsedPence`required	`integer`	Integer pence (GBP). Losses brought forward set against this year’s profits.
`lossesCf`required	`object (LossesBroughtForward)`	Losses carried forward, including any trading loss of this year.
`lossesCf.pre2017Pence`required	`integer`	Integer pence (GBP). at least 0
`lossesCf.post2017Pence`required	`integer`	Integer pence (GBP). at least 0
`taxableProfitsPence`required	`integer`	Whole pounds (floored), in pence.
`corporationTaxPence`required	`integer`	Integer pence (GBP).
`marginalReliefPence`required	`integer`	Integer pence (GBP).
`rateBand`required	`string`	The rate band in plain words, e.g. "Main rate 25%" or "Marginal relief applies".
`chargeLabel`required	`string`	The tax before marginal relief, e.g. "Corporation tax at 25% on £127,600".
`accountingPeriods`	`array of TaxAccountingPeriod`	One per accounting period; the totals above add them up.
`accountingPeriods[].start`required	`string (date)`	example "2026-03-31"
`accountingPeriods[].end`required	`string (date)`	example "2026-03-31"
`accountingPeriods[].days`required	`integer`
`accountingPeriods[].adjustedProfitPence`required	`integer`	Integer pence (GBP). Adjusted trading profit before capital allowances, apportioned by days (CTA 2010 s1172).
`accountingPeriods[].capitalAllowancesPence`required	`integer`	Integer pence (GBP). Capital allowances for this period, net of balancing charges (CAA 2001 s6).
`accountingPeriods[].lossesUsedPence`required	`integer`	Integer pence (GBP).
`accountingPeriods[].taxableProfitsPence`required	`integer`	Whole pounds (floored), in pence.
`accountingPeriods[].roundedDownPence`required	`integer`	Integer pence (GBP). Taken off by rounding down to whole pounds in this period.
`accountingPeriods[].corporationTaxPence`required	`integer`	Integer pence (GBP).
`accountingPeriods[].marginalReliefPence`required	`integer`	Integer pence (GBP).
`accountingPeriods[].rateBand`required	`string`
`accountingPeriods[].chargeLabel`required	`string`
`accountingPeriods[].paymentDueDate`required	`string (date)`	9 months and 1 day after the accounting period ends (TMA 1970 s59D). example "2026-03-31"
`accountingPeriods[].ct600Reference`required	`string`	Which CT600 this is, e.g. "CT600 1 of 2: 1 January 2025 to 31 December 2025".
`accountingPeriods[].ct600DueDate`required	`string (date)`	FA 1998 Sch 18 para 14: set by the period of account, the same for each of its CT600s. example "2026-03-31"
`periodNote`	`string`nullable	Explains a period of account over 12 months: the split, the apportionment and the rounding per period.
`journalAccountsMapped`required	`boolean`	A corporation tax charge and creditor are mapped in the TB, so the tax journal can be posted.
`chargePerTbPence`required	`integer`	Integer pence (GBP).
`differencePence`required	`integer`	Integer pence (GBP). Computation less TB: the tax journal to post.
`deferred`required	`object (DeferredTax)`
`deferred.applies`required	`boolean`
`deferred.netBookValuePence`required	`integer`	Integer pence (GBP). NBV of assets that attract allowances, per the register (C final per the TB when there is no register).
`deferred.taxWrittenDownValuePence`required	`integer`	Integer pence (GBP).
`deferred.timingDifferencePence`required	`integer`	Integer pence (GBP).
`deferred.permanentDifferencePence`required	`integer`	Integer pence (GBP). NBV of assets that never attract allowances (FRS 102 s29.10): no deferred tax.
`deferred.lines`required	`array of DeferredTaxLine`	NBV against tax WDV by pool, single-asset pool or SBA asset, from the register.
`deferred.lines[].description`required	`string`
`deferred.lines[].netBookValuePence`required	`integer`	Integer pence (GBP).
`deferred.lines[].taxWrittenDownValuePence`required	`integer`	Integer pence (GBP).
`deferred.lines[].timingDifferencePence`required	`integer`	Integer pence (GBP).
`deferred.rateBps`required	`integer`
`deferred.provisionPence`required	`integer`	Integer pence (GBP). Provision required (liability positive).
`deferred.openingPence`required	`integer`	Integer pence (GBP).
`deferred.perTbPence`required	`integer`	Integer pence (GBP).
`deferred.differencePence`required	`integer`	Integer pence (GBP). Provision less TB: the deferred tax journal to post.
`deferred.journalAccountsMapped`required	`boolean`	A deferred tax charge and provision are mapped in the TB, so the deferred tax journal can be posted.
`warnings`required	`array of string`
`lockedReason`required	`string`nullable	Why a preparer cannot change the computation now (section T reviewed).
`inputsSetUp`	`boolean`	The preparer has saved the inputs (PUT …/tax/inputs) at least once, so the computation is set up.

Errors: 400 Bad request, 401 Unauthorised, 403 Forbidden, 404 Not found, 429 Too many requests, as problem details (application/problem+json).

Set tax inputs (associated companies, other adjustments)

PUT/api/v1/engagements/{id}/tax/inputs

Scopes: engagements:write and engagements:read

Capital allowances and pools brought forward come from the fixed asset register (C); the old fields are ignored. Part of the working_papers product: the firm must have it and you must have access to it.

Parameters

Parameters for PUT /api/v1/engagements/{id}/tax/inputs
Name	In	Type	Description
`id`required	path	`string (uuid)`	Engagement id.

Request body

Required. application/json: object (SetTaxInputs).

Capital allowances are set in the fixed asset register (C), not here.

Request body for PUT /api/v1/engagements/{id}/tax/inputs
Field	Type	Description
`associatedCompanies`required	`integer`	0 to 1000
`otherAdjustments`required	`array of TaxAdjustmentInput`	up to 100 items
`otherAdjustments[].description`required	`string`	up to 200 characters
`otherAdjustments[].amountPence`required	`integer`	Integer pence (GBP). Positive adds back, negative deducts.
`lossesBroughtForward`	`object (LossesBroughtForward)`	Trading losses brought forward. Omitted: unchanged (the roll forward sets them).
`lossesBroughtForward.pre2017Pence`required	`integer`	Integer pence (GBP). at least 0
`lossesBroughtForward.post2017Pence`required	`integer`	Integer pence (GBP). at least 0
`aiaPence`	`integer`nullable	Integer pence (GBP). Deprecated and ignored: set in the fixed asset register (C). deprecated
`mainPoolBfPence`	`integer`	Integer pence (GBP). Deprecated and ignored: set in the fixed asset register settings (C). deprecated
`specialRatePoolBfPence`	`integer`	Integer pence (GBP). Deprecated and ignored: set in the fixed asset register settings (C). deprecated
`disposalProceedsPence`	`integer`	Integer pence (GBP). Deprecated and ignored: record disposals in the fixed asset register (C). deprecated

Responses

200 OK, `application/json`

Body: object (TaxComputation).

The fields are as shown above.

Errors: 400 Bad request, 401 Unauthorised, 403 Forbidden, 404 Not found, 429 Too many requests, as problem details (application/problem+json).

Preview the tax or deferred tax journal

POST/api/v1/engagements/{id}/tax/journals/preview

Scopes: engagements:read

The journal that posting would make (lines, date and narrative), the earlier one it would replace, and what would change: sections whose content moves, sign-offs that go out of date and the headline figures. Nothing is saved. Read access is enough. Part of the working_papers product: the firm must have it and you must have access to it.

Parameters

Parameters for POST /api/v1/engagements/{id}/tax/journals/preview
Name	In	Type	Description
`id`required	path	`string (uuid)`	Engagement id.

Request body

Required. application/json: object (PreviewTaxJournal).

Request body for POST /api/v1/engagements/{id}/tax/journals/preview
Field	Type	Description
`kind`required	`string (TaxJournalKind)`	One of: `ct`, `deferred`

Responses

200 OK, `application/json`

Body: object (TaxJournalPreview).

The tax journal that posting would make, without posting it.

200 OK response for POST /api/v1/engagements/{id}/tax/journals/preview
Field	Type	Description
`kind`required	`string (TaxJournalKind)`	One of: `ct`, `deferred`
`date`required	`string (date)`	example "2026-03-31"
`narrative`required	`string`
`lines`required	`array of JournalLine`	Empty when the TB already agrees with the computation.
`lines[].accountCode`required	`string`
`lines[].accountName`required	`string`nullable
`lines[].debitPence`required	`integer`	Integer pence (GBP).
`lines[].creditPence`required	`integer`	Integer pence (GBP).
`replacesRef`required	`string`nullable	The earlier journal of this kind that posting would replace.
`replacesAmountPence`required	`integer`nullable	Integer pence (GBP). The total debits of the journal replaced.
`impact`required	`object (JournalImpact)`	What a journal change would do, worked out without saving anything.
`impact.sections`required	`array of SectionImpact`	Sections whose content would change, in file order.
`impact.sections[].code`required	`string`
`impact.sections[].name`required	`string`
`impact.sections[].staleSignOffs`required	`array of StaleSignOff`	Live sign-offs on the section that would go out of date.
`impact.sections[].staleSignOffs[].stageId`required	`string`
`impact.sections[].staleSignOffs[].stageName`required	`string`
`impact.sections[].staleSignOffs[].userId`required	`string (uuid)`
`impact.figures`required	`array of FigureChange`	Headline figures that would move.
`impact.figures[].key`required	`string (FigureKey)`	One of: `profit_before_tax`, `corporation_tax`, `tax_charge`, `net_profit`
`impact.figures[].label`required	`string`
`impact.figures[].beforePence`required	`integer`	Integer pence (GBP).
`impact.figures[].afterPence`required	`integer`	Integer pence (GBP).
`blockedReason`required	`string`nullable	Why the caller can’t post it now (T reviewed and the caller is a preparer); null when they can.

Errors: 400 Bad request, 401 Unauthorised, 403 Forbidden, 404 Not found, 429 Too many requests, as problem details (application/problem+json).

Post the tax or deferred tax journal

POST/api/v1/engagements/{id}/tax/journals

Scopes: engagements:write and engagements:read

Brings the TB into line with the computation. Preparers, reviewers, managers and partners can post it; the audit trail records who. Once T has a current review sign-off only a reviewer or above can (403 for a preparer). Part of the working_papers product: the firm must have it and you must have access to it.

Parameters

Parameters for POST /api/v1/engagements/{id}/tax/journals
Name	In	Type	Description
`id`required	path	`string (uuid)`	Engagement id.

Request body

Required. application/json: object (PostTaxJournal).

Request body for POST /api/v1/engagements/{id}/tax/journals
Field	Type	Description
`kind`required	`string (TaxJournalKind)`	One of: `ct`, `deferred`
`replace`	`boolean`	Replace an earlier tax journal of this kind (required when one exists).

Responses

200 OK, `application/json`

Body: object (TaxJournalResult).

200 OK response for POST /api/v1/engagements/{id}/tax/journals
Field	Type	Description
`journal`required	`object (Journal)`nullable	Null when the TB already agrees.
`journal.id`required	`string (uuid)`
`journal.ref`required	`string`	example "JNL-03"
`journal.date`required	`string (date)`	example "2026-03-31"
`journal.type`required	`string (JournalType)`	One of: `Adjusting`, `Reclassification`, `Correction`
`journal.status`required	`string (JournalStatus)`	One of: `draft`, `posted`
`journal.narrative`required	`string`
`journal.autoKind`required	`string (JournalAutoKind)`nullable	Posted by Tolvi from the tax computation (ct, deferred) or the fixed asset register (fixed_assets). One of: `ct`, `deferred`, `fixed_assets`
`journal.lines`required	`array of JournalLine`
`journal.lines[].accountCode`required	`string`
`journal.lines[].accountName`required	`string`nullable
`journal.lines[].debitPence`required	`integer`	Integer pence (GBP).
`journal.lines[].creditPence`required	`integer`	Integer pence (GBP).
`journal.sectionCodes`required	`array of string`	Lead sections the journal touches.
`journal.lockedBySections`required	`array of string`	Reviewed sections that lock it: only a reviewer or above can unpost or delete it.
`journal.createdBy`required	`string (uuid)`nullable
`journal.createdAt`required	`string (date-time)`
`journal.postedBy`required	`string (uuid)`nullable
`journal.postedAt`required	`string (date-time)`nullable
`replacedRef`required	`string`nullable
`computation`required	`object (TaxComputation)`
`computation.applies`required	`boolean`	Corporation tax applies (companies only).
`computation.error`required	`string`nullable
`computation.inputs`required	`object (TaxInputs)`	Tax inputs the TB cannot give. Capital allowances are not among them: they come from the fixed asset register (C).
`computation.inputs.associatedCompanies`required	`integer`	0 to 1000
`computation.inputs.aiaPence`required	`integer`nullable	Integer pence (GBP). Deprecated: capital allowances come from the fixed asset register (section C, /fixed-assets). Echoes the register’s figure. AIA claimed. deprecated
`computation.inputs.mainPoolBfPence`required	`integer`	Integer pence (GBP). Deprecated: capital allowances come from the fixed asset register (section C, /fixed-assets). Echoes the register’s figure. Main pool WDV b/f. at least 0; deprecated
`computation.inputs.specialRatePoolBfPence`required	`integer`	Integer pence (GBP). Deprecated: capital allowances come from the fixed asset register (section C, /fixed-assets). Echoes the register’s figure. Special rate pool WDV b/f. at least 0; deprecated
`computation.inputs.disposalProceedsPence`required	`integer`	Integer pence (GBP). Deprecated: capital allowances come from the fixed asset register (section C, /fixed-assets). Echoes the register’s figure. Disposal values deducted from the pools. at least 0; deprecated
`computation.inputs.otherAdjustments`required	`array of TaxAdjustmentInput`	up to 100 items
`computation.inputs.otherAdjustments[].description`required	`string`	up to 200 characters
`computation.inputs.otherAdjustments[].amountPence`required	`integer`	Integer pence (GBP). Positive adds back, negative deducts.
`computation.inputs.lossesBroughtForward`	`object (LossesBroughtForward)`	Last year’s losses carried forward (set by the roll forward). Absent: none.
`computation.inputs.lossesBroughtForward.pre2017Pence`required	`integer`	Integer pence (GBP). at least 0
`computation.inputs.lossesBroughtForward.post2017Pence`required	`integer`	Integer pence (GBP). at least 0
`computation.profitBeforeTaxPence`required	`integer`	Integer pence (GBP).
`computation.adjustments`required	`array of TaxAdjustmentLine`
`computation.adjustments[].description`required	`string`
`computation.adjustments[].amountPence`required	`integer`	Integer pence (GBP).
`computation.adjustments[].reference`required	`string`	Legislation or HMRC manual reference.
`computation.additionsPence`required	`integer`	Integer pence (GBP).
`computation.aiaPence`required	`integer`	Integer pence (GBP).
`computation.mainPoolPence`required	`integer`	Integer pence (GBP).
`computation.mainPoolWdaPence`required	`integer`	Integer pence (GBP).
`computation.specialRatePoolWdaPence`required	`integer`	Integer pence (GBP).
`computation.balancingChargePence`required	`integer`	Integer pence (GBP).
`computation.capitalAllowancesPence`required	`integer`	Integer pence (GBP). Allowances before balancing charges, from the fixed asset register (C).
`computation.fixedAssetRegister`required	`boolean`	Section C has a fixed asset register; without one no allowances are claimed.
`computation.mainPoolBfPence`required	`integer`	Integer pence (GBP).
`computation.specialRatePoolBfPence`required	`integer`	Integer pence (GBP).
`computation.disposalValuesPence`required	`integer`	Integer pence (GBP).
`computation.firstYearAllowancesPence`required	`integer`	Integer pence (GBP). Full expensing, special rate allowance and other first-year allowances.
`computation.otherAllowancesPence`required	`integer`	Integer pence (GBP). Single-asset pools, SBA and balancing allowances.
`computation.mainPoolCfPence`required	`integer`	Integer pence (GBP).
`computation.specialRatePoolCfPence`required	`integer`	Integer pence (GBP).
`computation.lossesBfPence`required	`integer`	Integer pence (GBP). Trading losses brought forward (both regimes).
`computation.lossesUsedPence`required	`integer`	Integer pence (GBP). Losses brought forward set against this year’s profits.
`computation.lossesCf`required	`object (LossesBroughtForward)`	Losses carried forward, including any trading loss of this year.
`computation.lossesCf.pre2017Pence`required	`integer`	Integer pence (GBP). at least 0
`computation.lossesCf.post2017Pence`required	`integer`	Integer pence (GBP). at least 0
`computation.taxableProfitsPence`required	`integer`	Whole pounds (floored), in pence.
`computation.corporationTaxPence`required	`integer`	Integer pence (GBP).
`computation.marginalReliefPence`required	`integer`	Integer pence (GBP).
`computation.rateBand`required	`string`	The rate band in plain words, e.g. "Main rate 25%" or "Marginal relief applies".
`computation.chargeLabel`required	`string`	The tax before marginal relief, e.g. "Corporation tax at 25% on £127,600".
`computation.accountingPeriods`	`array of TaxAccountingPeriod`	One per accounting period; the totals above add them up.
`computation.accountingPeriods[].start`required	`string (date)`	example "2026-03-31"
`computation.accountingPeriods[].end`required	`string (date)`	example "2026-03-31"
`computation.accountingPeriods[].days`required	`integer`
`computation.accountingPeriods[].adjustedProfitPence`required	`integer`	Integer pence (GBP). Adjusted trading profit before capital allowances, apportioned by days (CTA 2010 s1172).
`computation.accountingPeriods[].capitalAllowancesPence`required	`integer`	Integer pence (GBP). Capital allowances for this period, net of balancing charges (CAA 2001 s6).
`computation.accountingPeriods[].lossesUsedPence`required	`integer`	Integer pence (GBP).
`computation.accountingPeriods[].taxableProfitsPence`required	`integer`	Whole pounds (floored), in pence.
`computation.accountingPeriods[].roundedDownPence`required	`integer`	Integer pence (GBP). Taken off by rounding down to whole pounds in this period.
`computation.accountingPeriods[].corporationTaxPence`required	`integer`	Integer pence (GBP).
`computation.accountingPeriods[].marginalReliefPence`required	`integer`	Integer pence (GBP).
`computation.accountingPeriods[].rateBand`required	`string`
`computation.accountingPeriods[].chargeLabel`required	`string`
`computation.accountingPeriods[].paymentDueDate`required	`string (date)`	9 months and 1 day after the accounting period ends (TMA 1970 s59D). example "2026-03-31"
`computation.accountingPeriods[].ct600Reference`required	`string`	Which CT600 this is, e.g. "CT600 1 of 2: 1 January 2025 to 31 December 2025".
`computation.accountingPeriods[].ct600DueDate`required	`string (date)`	FA 1998 Sch 18 para 14: set by the period of account, the same for each of its CT600s. example "2026-03-31"
`computation.periodNote`	`string`nullable	Explains a period of account over 12 months: the split, the apportionment and the rounding per period.
`computation.journalAccountsMapped`required	`boolean`	A corporation tax charge and creditor are mapped in the TB, so the tax journal can be posted.
`computation.chargePerTbPence`required	`integer`	Integer pence (GBP).
`computation.differencePence`required	`integer`	Integer pence (GBP). Computation less TB: the tax journal to post.
`computation.deferred`required	`object (DeferredTax)`
`computation.deferred.applies`required	`boolean`
`computation.deferred.netBookValuePence`required	`integer`	Integer pence (GBP). NBV of assets that attract allowances, per the register (C final per the TB when there is no register).
`computation.deferred.taxWrittenDownValuePence`required	`integer`	Integer pence (GBP).
`computation.deferred.timingDifferencePence`required	`integer`	Integer pence (GBP).
`computation.deferred.permanentDifferencePence`required	`integer`	Integer pence (GBP). NBV of assets that never attract allowances (FRS 102 s29.10): no deferred tax.
`computation.deferred.lines`required	`array of DeferredTaxLine`	NBV against tax WDV by pool, single-asset pool or SBA asset, from the register.
`computation.deferred.lines[].description`required	`string`
`computation.deferred.lines[].netBookValuePence`required	`integer`	Integer pence (GBP).
`computation.deferred.lines[].taxWrittenDownValuePence`required	`integer`	Integer pence (GBP).
`computation.deferred.lines[].timingDifferencePence`required	`integer`	Integer pence (GBP).
`computation.deferred.rateBps`required	`integer`
`computation.deferred.provisionPence`required	`integer`	Integer pence (GBP). Provision required (liability positive).
`computation.deferred.openingPence`required	`integer`	Integer pence (GBP).
`computation.deferred.perTbPence`required	`integer`	Integer pence (GBP).
`computation.deferred.differencePence`required	`integer`	Integer pence (GBP). Provision less TB: the deferred tax journal to post.
`computation.deferred.journalAccountsMapped`required	`boolean`	A deferred tax charge and provision are mapped in the TB, so the deferred tax journal can be posted.
`computation.warnings`required	`array of string`
`computation.lockedReason`required	`string`nullable	Why a preparer cannot change the computation now (section T reviewed).
`computation.inputsSetUp`	`boolean`	The preparer has saved the inputs (PUT …/tax/inputs) at least once, so the computation is set up.

Errors: 400 Bad request, 401 Unauthorised, 403 Forbidden, 404 Not found, 429 Too many requests, as problem details (application/problem+json).

Get the self assessment computation

GET/api/v1/engagements/{id}/self-assessment

Scopes: engagements:read

Sole traders, partnerships and LLPs: adjusted profit, capital allowances, tax-year basis apportionment, transition profit, partner allocation, Class 4 NIC and the SA103 or SA800 figures. 404 for companies. Part of the working_papers product: the firm must have it and you must have access to it.

Parameters

Parameters for GET /api/v1/engagements/{id}/self-assessment
Name	In	Type	Description
`id`required	path	`string (uuid)`	Engagement id.

Responses

200 OK, `application/json`

Body: object (SelfAssessmentComputation).

200 OK response for GET /api/v1/engagements/{id}/self-assessment
Field	Type	Description
`entity`required	`string (SaEntity)`	One of: `sole_trader`, `partnership`, `llp`
`error`required	`string`nullable
`warnings`required	`array of string`
`inputs`required	`object (SelfAssessmentInputs)`
`inputs.accounts`required	`array of SaAccountTreatment`
`inputs.accounts[].code`required	`string`	Account code in the TB.
`inputs.accounts[].category`required	`string (Sa103ExpenseCategory)`nullable	SA103 expense line; null uses Tolvi’s suggestion. One of: `costOfGoods`, `constructionSubcontractors`, `wagesAndStaffCosts`, `carVanAndTravel`, `rentRatesPowerAndInsurance`, `repairsAndMaintenance`, `phoneFaxStationeryAndOffice`, `advertisingAndBusinessEntertainment`, `interestOnBankAndOtherLoans`, `bankCreditCardAndFinancialCharges`, `irrecoverableDebts`, `accountancyLegalAndProfessional`, `depreciationAndLossOnSale`, `otherBusinessExpenses`
`inputs.accounts[].disallowablePence`required	`integer`	Integer pence (GBP). Disallowable outright (fines, capital items). Depreciation and entertaining (M.dis) are always disallowed in full.
`inputs.accounts[].privateUsePercent`required	`number`nullable	Private-use share of the rest, in per cent; null = not considered yet (0 means none). 0 to 100
`inputs.goodsForOwnUsePence`required	`integer`	Integer pence (GBP). Goods taken for own use, at selling price (ITTOIA 2005 s172B).
`inputs.otherAdjustments`required	`array of SaAdjustmentInput`
`inputs.otherAdjustments[].description`required	`string`
`inputs.otherAdjustments[].amountPence`required	`integer`	Integer pence (GBP). Positive adds back, negative deducts.
`inputs.tradingAllowance`required	`string (TradingAllowanceChoice)`	Sole traders: auto claims the £1,000 trading allowance when it gives a lower profit. Never available for partnership income. One of: `auto`, `claim`, `none`
`inputs.lateAccountingDates`required	`boolean`	Treat a 31 March to 4 April year end as 5 April (ITTOIA 2005 s202B).
`inputs.commencementDate`required	`string (date)`nullable	example "2026-03-31"
`inputs.cessationDate`required	`string (date)`nullable	example "2026-03-31"
`inputs.otherPeriods`required	`array of SaOtherPeriod`	Other periods of account needed to apportion profit to the tax year (last year, or a provisional figure for next year).
`inputs.otherPeriods[].start`required	`string (date)`	example "2026-03-31"
`inputs.otherPeriods[].end`required	`string (date)`	example "2026-03-31"
`inputs.otherPeriods[].profitPence`required	`integer`	Integer pence (GBP). Tax-adjusted profit after capital allowances (negative for a loss).
`inputs.otherPeriods[].provisional`required	`boolean`	A provisional figure for a period not yet drawn up, to be amended once known.
`inputs.overlapReliefPence`required	`integer`	Integer pence (GBP). Sole trader: overlap relief brought forward (used in 2023/24).
`inputs.transitionProfitPence`required	`integer`	Integer pence (GBP). Sole trader: transition profit from 2023/24, spread over five years.
`inputs.lossesBroughtForwardPence`required	`integer`	Integer pence (GBP).
`inputs.partners`required	`array of SaPartner`
`inputs.partners[].id`required	`string`	Your own short id for the partner, used in the arrangements. up to 40 characters
`inputs.partners[].name`required	`string`
`inputs.partners[].kind`required	`string (SaPartnerKind)`	A company partner (or LLP corporate member) is charged to corporation tax on its share; no income tax working is done for it. One of: `individual`, `company`
`inputs.partners[].joined`required	`string (date)`nullable	example "2026-03-31"
`inputs.partners[].left`required	`string (date)`nullable	example "2026-03-31"
`inputs.partners[].overlapReliefPence`required	`integer`	Integer pence (GBP). Overlap relief brought forward, used in 2023/24.
`inputs.partners[].transitionProfitPence`required	`integer`	Integer pence (GBP). The partner’s transition profit from 2023/24, spread over five years.
`inputs.partners[].lossesBroughtForwardPence`required	`integer`	Integer pence (GBP).
`inputs.arrangements`required	`array of SaArrangement`
`inputs.arrangements[].from`required	`string (date)`	In force from this date until the next arrangement starts. example "2026-03-31"
`inputs.arrangements[].shares`required	`array of SaPartnerShare`
`inputs.arrangements[].shares[].partnerId`required	`string`
`inputs.arrangements[].shares[].ratio`required	`integer`	Residual profit-sharing ratio, as whole-number weights (e.g. 50/35/15). at least 0
`inputs.arrangements[].shares[].salaryPence`required	`integer`	Integer pence (GBP). Annual salary (prior share).
`inputs.arrangements[].shares[].interestPence`required	`integer`	Integer pence (GBP). Annual interest on capital.
`period`required	`object (SaDateRange)`
`period.start`required	`string (date)`	example "2026-03-31"
`period.end`required	`string (date)`	example "2026-03-31"
`accounts`required	`array of SaAccountRow`
`accounts[].code`required	`string`
`accounts[].name`required	`string`
`accounts[].lineId`required	`string`
`accounts[].amountPence`required	`integer`	Integer pence (GBP). Final TB balance, debit positive.
`accounts[].category`required	`string (Sa103ExpenseCategory)`	SA103 expense line; null uses Tolvi’s suggestion. One of: `costOfGoods`, `constructionSubcontractors`, `wagesAndStaffCosts`, `carVanAndTravel`, `rentRatesPowerAndInsurance`, `repairsAndMaintenance`, `phoneFaxStationeryAndOffice`, `advertisingAndBusinessEntertainment`, `interestOnBankAndOtherLoans`, `bankCreditCardAndFinancialCharges`, `irrecoverableDebts`, `accountancyLegalAndProfessional`, `depreciationAndLossOnSale`, `otherBusinessExpenses`
`accounts[].categorySuggested`required	`boolean`	The category is Tolvi’s suggestion, not the preparer’s.
`accounts[].disallowablePence`required	`integer`	Integer pence (GBP).
`accounts[].privateUsePercent`required	`number`nullable
`accounts[].privateUsePence`required	`integer`	Integer pence (GBP).
`accounts[].allowablePence`required	`integer`	Integer pence (GBP).
`accounts[].privateUseUnrecorded`required	`boolean`	The account usually has some private use (motor, phone, use of home) and none is recorded.
`profitPerAccountsPence`required	`integer`	Integer pence (GBP). Net profit per the final TB.
`turnoverPence`required	`integer`	Integer pence (GBP).
`interestReceivedPence`required	`integer`	Integer pence (GBP).
`adjustments`required	`array of SaLine`
`adjustments[].description`required	`string`
`adjustments[].amountPence`required	`integer`	Integer pence (GBP).
`adjustments[].reference`required	`string`	Legislation or HMRC manual reference.
`capitalAllowances`required	`object (SaCapitalAllowances)`
`capitalAllowances.fromRegister`required	`boolean`
`capitalAllowances.annualInvestmentAllowancePence`required	`integer`	Integer pence (GBP).
`capitalAllowances.firstYearAllowancesPence`required	`integer`	Integer pence (GBP).
`capitalAllowances.mainPoolWdaPence`required	`integer`	Integer pence (GBP).
`capitalAllowances.specialRatePoolWdaPence`required	`integer`	Integer pence (GBP).
`capitalAllowances.singleAssetPoolsPence`required	`integer`	Integer pence (GBP).
`capitalAllowances.structuresAndBuildingsPence`required	`integer`	Integer pence (GBP).
`capitalAllowances.balancingAllowancesPence`required	`integer`	Integer pence (GBP).
`capitalAllowances.totalPence`required	`integer`	Integer pence (GBP). Allowances claimed, after the private-use restriction.
`capitalAllowances.balancingChargesPence`required	`integer`	Integer pence (GBP).
`capitalAllowances.privateUseRestrictionPence`required	`integer`	Integer pence (GBP). Allowances not given because of private use (CAA 2001 s207).
`capitalAllowances.singleAssetPools`required	`array of SaSingleAssetPool`
`capitalAllowances.singleAssetPools[].assetId`required	`string`
`capitalAllowances.singleAssetPools[].ref`required	`string`
`capitalAllowances.singleAssetPools[].description`required	`string`
`capitalAllowances.singleAssetPools[].businessUsePercent`required	`number`
`capitalAllowances.singleAssetPools[].allowancePence`required	`integer`	Integer pence (GBP). Allowance before the private-use restriction.
`capitalAllowances.singleAssetPools[].aiaPence`required	`integer`	Integer pence (GBP). Of the allowance before the restriction, the Annual Investment Allowance (CAA 2001 s51A).
`capitalAllowances.singleAssetPools[].claimedPence`required	`integer`	Integer pence (GBP). Allowance claimed (business share).
`capitalAllowances.mainPoolCfPence`required	`integer`	Integer pence (GBP).
`capitalAllowances.specialRatePoolCfPence`required	`integer`	Integer pence (GBP).
`adjustedProfitActualPence`required	`integer`	Integer pence (GBP).
`tradingAllowanceClaimed`required	`string (TradingAllowanceClaimed)`	One of: `none`, `full-relief`, `partial-relief`
`adjustedProfitPence`required	`integer`	Integer pence (GBP). Tax-adjusted trading profit of the period (after capital allowances and any trading allowance).
`taxYears`required	`array of SaTaxYearShare`
`taxYears[].taxYear`required	`integer`
`taxYears[].label`required	`string`	example "2025/26"
`taxYears[].start`required	`string (date)`	example "2026-03-31"
`taxYears[].end`required	`string (date)`	example "2026-03-31"
`taxYears[].days`required	`integer`
`taxYears[].periodDays`required	`integer`
`taxYears[].sharePence`required	`integer`	Integer pence (GBP).
`returnTaxYear`required	`integer`
`returnTaxYearLabel`required	`string`
`missingPeriods`required	`array of SaDateRange`
`missingPeriods[].start`required	`string (date)`	example "2026-03-31"
`missingPeriods[].end`required	`string (date)`	example "2026-03-31"
`soleTrader`required	`object (SaSoleTrader)`nullable
`soleTrader.working`required	`object (SaTaxYearWorking)`nullable	Null until every period needed for the return year has a figure.
`soleTrader.working.taxYear`required	`integer`
`soleTrader.working.label`required	`string`
`soleTrader.working.basisPeriod`required	`object (SaDateRange)`
`soleTrader.working.basisPeriod.start`required	`string (date)`	example "2026-03-31"
`soleTrader.working.basisPeriod.end`required	`string (date)`	example "2026-03-31"
`soleTrader.working.apportionments`required	`array of SaApportionment`
`soleTrader.working.apportionments[].start`required	`string (date)`	example "2026-03-31"
`soleTrader.working.apportionments[].end`required	`string (date)`	example "2026-03-31"
`soleTrader.working.apportionments[].source`required	`string (SaPeriodSource)`	One of: `this`, `other`, `provisional`
`soleTrader.working.apportionments[].days`required	`integer`
`soleTrader.working.apportionments[].daysInBasisPeriod`required	`integer`
`soleTrader.working.apportionments[].profitPence`required	`integer`	Integer pence (GBP).
`soleTrader.working.apportionments[].sharePence`required	`integer`	Integer pence (GBP).
`soleTrader.working.basisPeriodProfitPence`required	`integer`	Integer pence (GBP).
`soleTrader.working.transition`required	`object (SaTransition)`nullable
`soleTrader.working.transition.standardPart`required	`object (SaDateRange)`nullable
`soleTrader.working.transition.standardPart.start`required	`string (date)`	example "2026-03-31"
`soleTrader.working.transition.standardPart.end`required	`string (date)`	example "2026-03-31"
`soleTrader.working.transition.standardPartProfitPence`required	`integer`	Integer pence (GBP).
`soleTrader.working.transition.transitionPart`required	`object (SaDateRange)`nullable
`soleTrader.working.transition.transitionPart.start`required	`string (date)`	example "2026-03-31"
`soleTrader.working.transition.transitionPart.end`required	`string (date)`	example "2026-03-31"
`soleTrader.working.transition.transitionPartProfitPence`required	`integer`	Integer pence (GBP).
`soleTrader.working.transition.overlapReliefPence`required	`integer`	Integer pence (GBP).
`soleTrader.working.transition.excessOverlapReliefPence`required	`integer`	Integer pence (GBP).
`soleTrader.working.transition.transitionProfitPence`required	`integer`	Integer pence (GBP).
`soleTrader.working.transition.spread`required	`array of SaSpreadYear`
`soleTrader.working.transition.spread[].taxYear`required	`integer`
`soleTrader.working.transition.spread[].label`required	`string`
`soleTrader.working.transition.spread[].amountPence`required	`integer`	Integer pence (GBP).
`soleTrader.working.transition.thisYearPence`required	`integer`	Integer pence (GBP). Transition profit taxed in this tax year.
`soleTrader.working.lossesBroughtForwardUsedPence`required	`integer`	Integer pence (GBP).
`soleTrader.working.taxableProfitPence`required	`integer`	Whole pounds (floored), in pence.
`soleTrader.working.lossPence`required	`integer`	Integer pence (GBP).
`soleTrader.working.lossCarriedForwardPence`required	`integer`	Integer pence (GBP).
`soleTrader.working.class4`required	`object (SaClass4)`
`soleTrader.working.class4.taxYear`required	`integer`
`soleTrader.working.class4.profits`required	`integer`	Integer pence (GBP).
`soleTrader.working.class4.mainRateBand`required	`integer`	Integer pence (GBP).
`soleTrader.working.class4.mainRateNic`required	`integer`	Integer pence (GBP).
`soleTrader.working.class4.additionalRateBand`required	`integer`	Integer pence (GBP).
`soleTrader.working.class4.additionalRateNic`required	`integer`	Integer pence (GBP).
`soleTrader.working.class4.total`required	`integer`	Integer pence (GBP).
`soleTrader.working.class2`required	`object (SaClass2)`
`soleTrader.working.class2.taxYear`required	`integer`
`soleTrader.working.class2.status`required	`string (SaClass2Status)`	One of: `payable`, `treated-as-paid`, `voluntary`
`soleTrader.working.class2.weeklyRate`required	`integer`	Integer pence (GBP).
`soleTrader.working.class2.payable`required	`integer`	Compulsory Class 2 (nil from 2024/25).
`soleTrader.working.class2.voluntaryAnnualCost`required	`integer`	Cost of a full year of voluntary contributions, where relevant.
`soleTrader.sa103`required	`object (Sa103Figures)`nullable
`soleTrader.sa103.pages`required	`string (SelfEmploymentPages)`	Short pages (SA103S) below the VAT registration threshold, else full (SA103F). One of: `short`, `full`
`soleTrader.sa103.turnoverPence`required	`integer`	Integer pence (GBP).
`soleTrader.sa103.otherBusinessIncomePence`required	`integer`	Integer pence (GBP).
`soleTrader.sa103.expenses`required	`array of SaExpenseLine`
`soleTrader.sa103.expenses[].category`required	`string (Sa103ExpenseCategory)`	SA103 expense line; null uses Tolvi’s suggestion. One of: `costOfGoods`, `constructionSubcontractors`, `wagesAndStaffCosts`, `carVanAndTravel`, `rentRatesPowerAndInsurance`, `repairsAndMaintenance`, `phoneFaxStationeryAndOffice`, `advertisingAndBusinessEntertainment`, `interestOnBankAndOtherLoans`, `bankCreditCardAndFinancialCharges`, `irrecoverableDebts`, `accountancyLegalAndProfessional`, `depreciationAndLossOnSale`, `otherBusinessExpenses`
`soleTrader.sa103.expenses[].label`required	`string`
`soleTrader.sa103.expenses[].totalPence`required	`integer`	Integer pence (GBP).
`soleTrader.sa103.expenses[].disallowablePence`required	`integer`	Integer pence (GBP).
`soleTrader.sa103.totalExpensesPence`required	`integer`	Integer pence (GBP).
`soleTrader.sa103.netProfitPence`required	`integer`	Integer pence (GBP).
`soleTrader.sa103.goodsForOwnUsePence`required	`integer`	Integer pence (GBP).
`soleTrader.sa103.disallowableExpensesPence`required	`integer`	Integer pence (GBP).
`soleTrader.sa103.balancingChargesPence`required	`integer`	Integer pence (GBP).
`soleTrader.sa103.capitalAllowancesPence`required	`integer`	Integer pence (GBP).
`soleTrader.sa103.tradingAllowanceClaimed`required	`boolean`
`soleTrader.sa103.adjustedProfitPence`required	`integer`	Integer pence (GBP).
`soleTrader.sa103.basisPeriodAdjustmentPence`required	`integer`	Integer pence (GBP).
`soleTrader.sa103.transitionProfitPence`required	`integer`	Integer pence (GBP).
`soleTrader.sa103.lossesBroughtForwardUsedPence`required	`integer`	Integer pence (GBP).
`soleTrader.sa103.taxableProfitPence`required	`integer`	Integer pence (GBP).
`soleTrader.sa103.class4Pence`required	`integer`	Integer pence (GBP).
`partnership`required	`object (SaPartnership)`nullable
`partnership.segments`required	`array of SaSegment`
`partnership.segments[].start`required	`string (date)`	example "2026-03-31"
`partnership.segments[].end`required	`string (date)`	example "2026-03-31"
`partnership.segments[].days`required	`integer`
`partnership.segments[].profitPence`required	`integer`	Integer pence (GBP).
`partnership.segments[].partners`required	`array of SaSegmentPartner`
`partnership.segments[].partners[].partnerId`required	`string`
`partnership.segments[].partners[].salaryPence`required	`integer`	Integer pence (GBP).
`partnership.segments[].partners[].interestPence`required	`integer`	Integer pence (GBP).
`partnership.segments[].partners[].residualSharePence`required	`integer`	Integer pence (GBP).
`partnership.segments[].partners[].totalPence`required	`integer`	Integer pence (GBP).
`partnership.partners`required	`array of SaPartnerResult`
`partnership.partners[].id`required	`string`
`partnership.partners[].name`required	`string`
`partnership.partners[].kind`required	`string (SaPartnerKind)`	A company partner (or LLP corporate member) is charged to corporation tax on its share; no income tax working is done for it. One of: `individual`, `company`
`partnership.partners[].joined`required	`string (date)`nullable	example "2026-03-31"
`partnership.partners[].left`required	`string (date)`nullable	example "2026-03-31"
`partnership.partners[].salaryPence`required	`integer`	Integer pence (GBP).
`partnership.partners[].interestPence`required	`integer`	Integer pence (GBP).
`partnership.partners[].residualSharePence`required	`integer`	Integer pence (GBP).
`partnership.partners[].notionalSharePence`required	`integer`	Integer pence (GBP). Share before any reallocation of notional losses (ITTOIA 2005 s850A/s850B).
`partnership.partners[].sharePence`required	`integer`	Integer pence (GBP). Share of the tax-adjusted profit: the partnership statement figure.
`partnership.partners[].accountingSharePence`required	`integer`	Integer pence (GBP). Share of the accounting profit per the arrangement.
`partnership.partners[].taxYears`required	`array of SaTaxYearShare`
`partnership.partners[].taxYears[].taxYear`required	`integer`
`partnership.partners[].taxYears[].label`required	`string`	example "2025/26"
`partnership.partners[].taxYears[].start`required	`string (date)`	example "2026-03-31"
`partnership.partners[].taxYears[].end`required	`string (date)`	example "2026-03-31"
`partnership.partners[].taxYears[].days`required	`integer`
`partnership.partners[].taxYears[].periodDays`required	`integer`
`partnership.partners[].taxYears[].sharePence`required	`integer`	Integer pence (GBP).
`partnership.partners[].working`required	`object (SaTaxYearWorking)`nullable	Individuals only.
`partnership.partners[].working.taxYear`required	`integer`
`partnership.partners[].working.label`required	`string`
`partnership.partners[].working.basisPeriod`required	`object (SaDateRange)`
`partnership.partners[].working.basisPeriod.start`required	`string (date)`	example "2026-03-31"
`partnership.partners[].working.basisPeriod.end`required	`string (date)`	example "2026-03-31"
`partnership.partners[].working.apportionments`required	`array of SaApportionment`
`partnership.partners[].working.apportionments[].start`required	`string (date)`	example "2026-03-31"
`partnership.partners[].working.apportionments[].end`required	`string (date)`	example "2026-03-31"
`partnership.partners[].working.apportionments[].source`required	`string (SaPeriodSource)`	One of: `this`, `other`, `provisional`
`partnership.partners[].working.apportionments[].days`required	`integer`
`partnership.partners[].working.apportionments[].daysInBasisPeriod`required	`integer`
`partnership.partners[].working.apportionments[].profitPence`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.apportionments[].sharePence`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.basisPeriodProfitPence`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.transition`required	`object (SaTransition)`nullable
`partnership.partners[].working.transition.standardPart`required	`object (SaDateRange)`nullable
`partnership.partners[].working.transition.standardPart.start`required	`string (date)`	example "2026-03-31"
`partnership.partners[].working.transition.standardPart.end`required	`string (date)`	example "2026-03-31"
`partnership.partners[].working.transition.standardPartProfitPence`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.transition.transitionPart`required	`object (SaDateRange)`nullable
`partnership.partners[].working.transition.transitionPart.start`required	`string (date)`	example "2026-03-31"
`partnership.partners[].working.transition.transitionPart.end`required	`string (date)`	example "2026-03-31"
`partnership.partners[].working.transition.transitionPartProfitPence`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.transition.overlapReliefPence`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.transition.excessOverlapReliefPence`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.transition.transitionProfitPence`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.transition.spread`required	`array of SaSpreadYear`
`partnership.partners[].working.transition.spread[].taxYear`required	`integer`
`partnership.partners[].working.transition.spread[].label`required	`string`
`partnership.partners[].working.transition.spread[].amountPence`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.transition.thisYearPence`required	`integer`	Integer pence (GBP). Transition profit taxed in this tax year.
`partnership.partners[].working.lossesBroughtForwardUsedPence`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.taxableProfitPence`required	`integer`	Whole pounds (floored), in pence.
`partnership.partners[].working.lossPence`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.lossCarriedForwardPence`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.class4`required	`object (SaClass4)`
`partnership.partners[].working.class4.taxYear`required	`integer`
`partnership.partners[].working.class4.profits`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.class4.mainRateBand`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.class4.mainRateNic`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.class4.additionalRateBand`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.class4.additionalRateNic`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.class4.total`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.class2`required	`object (SaClass2)`
`partnership.partners[].working.class2.taxYear`required	`integer`
`partnership.partners[].working.class2.status`required	`string (SaClass2Status)`	One of: `payable`, `treated-as-paid`, `voluntary`
`partnership.partners[].working.class2.weeklyRate`required	`integer`	Integer pence (GBP).
`partnership.partners[].working.class2.payable`required	`integer`	Compulsory Class 2 (nil from 2024/25).
`partnership.partners[].working.class2.voluntaryAnnualCost`required	`integer`	Cost of a full year of voluntary contributions, where relevant.
`partnership.partners[].missingPeriods`required	`array of SaDateRange`
`partnership.partners[].missingPeriods[].start`required	`string (date)`	example "2026-03-31"
`partnership.partners[].missingPeriods[].end`required	`string (date)`	example "2026-03-31"
`partnership.partners[].error`required	`string`nullable
`partnership.reallocated`required	`boolean`
`partnership.unallocatedPence`required	`integer`	Integer pence (GBP).
`partnership.sa800`required	`object (Sa800Figures)`
`partnership.sa800.turnoverPence`required	`integer`	Integer pence (GBP).
`partnership.sa800.accountingProfitPence`required	`integer`	Integer pence (GBP).
`partnership.sa800.taxAdjustedProfitPence`required	`integer`	Integer pence (GBP).
`partnership.sa800.sharesAgree`required	`boolean`
`privateUseUnrecorded`required	`object (SaPrivateUseUnrecorded)`
`privateUseUnrecorded.accounts`required	`array of string`
`privateUseUnrecorded.assets`required	`array of SaPrivateUseAsset`
`privateUseUnrecorded.assets[].id`required	`string`
`privateUseUnrecorded.assets[].ref`required	`string`
`drawingsPence`required	`integer`	Integer pence (GBP). Drawings per the final TB (debit positive).
`allocatedToMembersPerTbPence`required	`integer`	Integer pence (GBP). LLP: profit allocated to members per the final TB (debit positive).
`summary`required	`object (SaSummary)`	The overview stat: the taxable profit (sole traders) or the amount allocated to partners or members.
`summary.label`required	`string`	example "Taxable profit 2025/26"
`summary.valuePence`required	`integer`	Integer pence (GBP).
`summary.detail`required	`string`
`lockedReason`required	`string`nullable	Why a preparer cannot change the inputs now (section T reviewed).
`inputsSetUp`	`boolean`	The preparer has saved the inputs (PUT …/self-assessment/inputs) at least once, so the computation is set up.

Errors: 400 Bad request, 401 Unauthorised, 403 Forbidden, 404 Not found, 429 Too many requests, as problem details (application/problem+json).

Set the self assessment inputs

PUT/api/v1/engagements/{id}/self-assessment/inputs

Scopes: engagements:write and engagements:read

Replaces the whole set: expense treatment, adjustments, other periods of account, transition and overlap figures, partners and the profit-sharing arrangement. Locked to reviewers once T is reviewed. Part of the working_papers product: the firm must have it and you must have access to it.

Parameters

Parameters for PUT /api/v1/engagements/{id}/self-assessment/inputs
Name	In	Type	Description
`id`required	path	`string (uuid)`	Engagement id.

Request body

Required. application/json: object (SetSelfAssessmentInputs).

Request body for PUT /api/v1/engagements/{id}/self-assessment/inputs
Field	Type	Description
`accounts`	`array of SaAccountTreatment`
`accounts[].code`required	`string`	Account code in the TB.
`accounts[].category`required	`string (Sa103ExpenseCategory)`nullable	SA103 expense line; null uses Tolvi’s suggestion. One of: `costOfGoods`, `constructionSubcontractors`, `wagesAndStaffCosts`, `carVanAndTravel`, `rentRatesPowerAndInsurance`, `repairsAndMaintenance`, `phoneFaxStationeryAndOffice`, `advertisingAndBusinessEntertainment`, `interestOnBankAndOtherLoans`, `bankCreditCardAndFinancialCharges`, `irrecoverableDebts`, `accountancyLegalAndProfessional`, `depreciationAndLossOnSale`, `otherBusinessExpenses`
`accounts[].disallowablePence`required	`integer`	Integer pence (GBP). Disallowable outright (fines, capital items). Depreciation and entertaining (M.dis) are always disallowed in full.
`accounts[].privateUsePercent`required	`number`nullable	Private-use share of the rest, in per cent; null = not considered yet (0 means none). 0 to 100
`goodsForOwnUsePence`	`integer`	Integer pence (GBP).
`otherAdjustments`	`array of SaAdjustmentInput`
`otherAdjustments[].description`required	`string`
`otherAdjustments[].amountPence`required	`integer`	Integer pence (GBP). Positive adds back, negative deducts.
`tradingAllowance`	`string (TradingAllowanceChoice)`	Sole traders: auto claims the £1,000 trading allowance when it gives a lower profit. Never available for partnership income. One of: `auto`, `claim`, `none`
`lateAccountingDates`	`boolean`
`commencementDate`	`string (date)`nullable	example "2026-03-31"
`cessationDate`	`string (date)`nullable	example "2026-03-31"
`otherPeriods`	`array of SaOtherPeriod`
`otherPeriods[].start`required	`string (date)`	example "2026-03-31"
`otherPeriods[].end`required	`string (date)`	example "2026-03-31"
`otherPeriods[].profitPence`required	`integer`	Integer pence (GBP). Tax-adjusted profit after capital allowances (negative for a loss).
`otherPeriods[].provisional`required	`boolean`	A provisional figure for a period not yet drawn up, to be amended once known.
`overlapReliefPence`	`integer`	Integer pence (GBP).
`transitionProfitPence`	`integer`	Integer pence (GBP).
`lossesBroughtForwardPence`	`integer`	Integer pence (GBP).
`partners`	`array of SaPartner`
`partners[].id`required	`string`	Your own short id for the partner, used in the arrangements. up to 40 characters
`partners[].name`required	`string`
`partners[].kind`required	`string (SaPartnerKind)`	A company partner (or LLP corporate member) is charged to corporation tax on its share; no income tax working is done for it. One of: `individual`, `company`
`partners[].joined`required	`string (date)`nullable	example "2026-03-31"
`partners[].left`required	`string (date)`nullable	example "2026-03-31"
`partners[].overlapReliefPence`required	`integer`	Integer pence (GBP). Overlap relief brought forward, used in 2023/24.
`partners[].transitionProfitPence`required	`integer`	Integer pence (GBP). The partner’s transition profit from 2023/24, spread over five years.
`partners[].lossesBroughtForwardPence`required	`integer`	Integer pence (GBP).
`arrangements`	`array of SaArrangement`
`arrangements[].from`required	`string (date)`	In force from this date until the next arrangement starts. example "2026-03-31"
`arrangements[].shares`required	`array of SaPartnerShare`
`arrangements[].shares[].partnerId`required	`string`
`arrangements[].shares[].ratio`required	`integer`	Residual profit-sharing ratio, as whole-number weights (e.g. 50/35/15). at least 0
`arrangements[].shares[].salaryPence`required	`integer`	Integer pence (GBP). Annual salary (prior share).
`arrangements[].shares[].interestPence`required	`integer`	Integer pence (GBP). Annual interest on capital.

Responses

200 OK, `application/json`

Body: object (SelfAssessmentComputation).

The fields are as shown above.

Errors: 400 Bad request, 401 Unauthorised, 403 Forbidden, 404 Not found, 429 Too many requests, as problem details (application/problem+json).

Tax

Get the corporation tax computation

Parameters

Responses

200 OK, application/json

Set tax inputs (associated companies, other adjustments)

Parameters

Request body

Responses

200 OK, application/json

Preview the tax or deferred tax journal

Parameters

Request body

Responses

200 OK, application/json

Post the tax or deferred tax journal

Parameters

Request body

Responses

200 OK, application/json

Get the self assessment computation

Parameters

Responses

200 OK, application/json

Set the self assessment inputs

Parameters

Request body

Responses

200 OK, application/json

200 OK, `application/json`

200 OK, `application/json`

200 OK, `application/json`

200 OK, `application/json`

200 OK, `application/json`

200 OK, `application/json`