Use the FRC taxonomy version that matches the accounts framework, reporting period, software support and filing route. Do not assume the prior-year taxonomy remains correct; check current FRC and software guidance before final validation.
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.
Start with the accounts framework
The taxonomy version decision starts with the accounts framework, such as UK GAAP or IFRS, and the reporting period covered by the accounts.
- Confirm the financial reporting framework.
- Confirm the accounting period end.
- Check whether small or micro-entity formats affect the taxonomy route.
Check software and regulator support
The selected taxonomy must be supported by the preparation software and accepted by the intended filing workflow. A taxonomy can be conceptually right but still unavailable or unsuitable in a specific tool route.
- Check software release notes or taxonomy settings.
- Check HMRC or Companies House route constraints where relevant.
- Record the taxonomy version used in the filing pack.
Do not reuse without review
Prior-year taxonomy settings are useful evidence, but they should not be reused without checking framework changes, taxonomy updates and changes in the accounts.
- Compare current accounts to prior year.
- Review new disclosures and changed line items.
- Validate with the selected taxonomy before submission.
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
- Framework identified.
- Reporting period checked.
- Software taxonomy support confirmed.
- Filing route constraints checked.
- Version recorded with validation evidence.
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.