The UK GAAP taxonomy is used when UK GAAP accounts need iXBRL tagging. Preparers should map each material line item and disclosure to the concept that best reflects accounting meaning, then validate the tagged accounts before filing.
This guide is source-linked to official HMRC, Companies House and FRC material where available. Check current official guidance before treating the filing route, deadline or taxonomy choice as final.
When UK GAAP taxonomy applies
The UK GAAP taxonomy is relevant where the company prepares accounts under UK GAAP and those accounts are tagged for digital filing. The exact taxonomy route depends on the accounts type, period and software support.
- Confirm the accounts basis before tagging.
- Check small, micro-entity or other accounts format assumptions.
- Avoid using IFRS taxonomy concepts for UK GAAP accounts unless specifically appropriate.
Mapping by accounting meaning
UK GAAP mapping should follow the meaning of the accounts line item or disclosure. The nearest visible label is only a starting point; the reviewer should consider presentation, note context and accounting policy.
- Review profit and loss, balance sheet and notes.
- Check sign conventions for liabilities, losses and credits.
- Escalate unusual disclosures before filing.
Evidence to keep
The workpaper should show why the selected concepts were appropriate and how validation issues were resolved.
- Retain source accounts version.
- Retain mapping review comments.
- Retain validation and correction evidence.
Common risks
Common risks include treating HMRC and Companies House as one combined filing, using an old taxonomy assumption, copying prior-year tags without review, ignoring validation warnings, missing separate deadlines and losing evidence of approval.
- Do not rely only on prior-year files.
- Do not treat validation as a substitute for accounting or tax review.
- Escalate unusual balances, late filings or regulator-specific issues early.
Evidence to retain
The filing record should show the source accounts used, the HMRC or Companies House route decision, mapping or tagging review, validation results, corrections, approvals and final filing confirmation.
- Save signed or approved accounts and version details.
- Save validation and correction evidence for iXBRL files.
- Save HMRC, Companies House, upload or adviser handoff confirmation.
Before you rely on this route
- UK GAAP basis confirmed.
- Accounts format confirmed.
- Material line items mapped.
- Notes and disclosures reviewed.
- Validation evidence retained.
Official sources
Use these official references as the current regulatory baseline before making filing decisions.
FAQs
What is the short answer?
UK iXBRL tagging should use the applicable FRC taxonomy and accounting meaning from the source accounts. Teams should avoid label-only matching, validate the tagged file, and retain review evidence before HMRC or Companies House submission.
Are HMRC and Companies House filings the same?
No. Companies House accounts filing and HMRC Company Tax Return filing are separate UK obligations, even where the same statutory accounts support both workflows.
Can prior-year iXBRL files be reused?
Prior-year files can be a reference, but the current company facts, accounts, taxonomy, validation rules and official filing route should be checked again.
When should professional review be used?
Use professional review when the route is unclear, the filing is late, source documents changed, CT600 or tax computations changed, or the entity has unusual disclosures.
This article is general UK iXBRL filing information, not legal, tax, accounting or regulatory advice. Check current HMRC, Companies House and FRC guidance, and seek professional advice before making filing decisions.