Partner Filing API versioning and changelog

Versioning

Version policy and current exclusions

The current contract is v1.2.0. After a major version change, the previous major remains supported for 12 months. Frozen requests are replayed against canonical tax, return boxes, CT600 bodies, accounts and the generation digest. New required answers and treatment changes require a major version or a dated notice period of at least 90 days. Regulatory corrections identify their official source and receive a dated notice. A representation-only change is permitted only when those filing outputs remain equal.

• Browser navigation, session caches and display state have no filing meaning. Their data fields are classified as browser-only in the shared form contract.
• The planned customer AI assistant remains draft-only under PROJECT_AI_INSTRUCTIONS section 2b. It cannot declare, submit or handle credentials.
• An unresolved filing setup has no filing to admit. Supply the missing answers through the same shared fields; incomplete dry runs report those fields.
• The browser helper can display dates while the customer is unsure which return to file. This display-only state does not submit or prepare a return. The API requires the customer to choose the filing operation before admission.

Release notes

• 10 November 2026: filing scenario request examples are published in /api/v1/examples.json. The OpenAPI file carries captured calls only.
• 8 November 2026: added the form fields non_trade_deficit_current_claim, non_trade_deficit_current_claim_second_return and non_trading_loan_write_offs.
• 10 November 2026: endpoint reference enrichment. Described operations, parameters, typed success bodies, actual statuses and error codes, and captured call-specific examples. Fixed 50-item ID pagination is documented. The owner-authorised unpublished OpenAPI correction retains version 1.2.0, all frozen filing corpora and unchanged runtime responses.
• 9 November 2026, N5: directors disclosure record names stay with their first details across printed page boundaries. Values and request fields are unchanged. The authorised unpublished output recapture retains the original-baseline proof and fresh inactivity check.
• 9 November 2026, accounts review response: right-aligned year and currency headings, restored light note boxes with per-page grouping and adjusted cover typography. Original facts, figures, request fields and versions stay unchanged. The authorised unpublished corpus replacement uses the original pre-feature baseline and a fresh inactivity check.
• 9 November 2026, accounts revision 16: centred covers and headers, end-year columns, dotted contents, whole balance-sheet tables and denser continued notes. Original logical facts, figures and CT600 boxes are unchanged. The owner-approved unpublished corpus replacement compares against the original pre-feature baseline, with a fresh inactivity check before writing. Request fields, versions and the compatibility comparator are unchanged.
• 9 November 2026: accounts narrative fields now accept 8,000 sanitised characters. Enabled estimated-figures explanations have the same 8,000-character boundary in API preflight. This explanation refusal is new for the API. Inactive explanation text does not trigger it. Overlong text is refused without truncation.
• 9 November 2026: generated accounts have comma-grouped amounts, cover and contents, company headers and filed page numbers. Values and CT600 boxes are unchanged. The owner authorised a one-off recapture of all three unpublished frozen filing corpora after read-only checks found no partner activity and the display-only proof passed. No version or comparator change.