iXBRL tagging for small company accounts
Prepare small company accounts data so iXBRL tagging, CT600 filing and Companies House submission agree.
Companies House filing is becoming more software-led, and accounts preparation needs to be clean before the filing window opens. The accounts used for tax filing and statutory filing should come from the same clean numbers, even where the filing destinations differ. This guide covers iXBRL tagging readiness for UK companies that want fewer surprises at approval and submission.
For wider context, use Year-end and annual accounts . If the topic affects a filing deadline, software choice or tax treatment, confirm the live position before acting. The workflow below is designed to keep the evidence in one place so the owner, bookkeeper and accountant can all review the same record.
Official point to verify
GOV.UK accounts guidance gives current Companies House filing duties and states that from 1 April 2028 small companies and micro-entities must deliver a profit and loss account, with opt out details for publication still to be confirmed. Check the current wording in GOV.UK preparing and filing company accounts guidance before making a binding filing, software or tax decision.
What to control
| Area | Control | Why it matters |
|---|---|---|
| Final accounts | Lock the version used for tagging | Tagged data should match approved accounts |
| Tax computation | Tie profit before tax to the CT600 workpapers | HMRC filing needs a bridge from accounts to tax |
| Notes | Review disclosures before export | Tagging does not fix missing disclosure |
| Version control | Store the tagged file with the filing pack | Future queries need the exact submitted version |
Review routine
Treat the accounts file as a controlled data pack. Reconcile the trial balance, agree disclosures, confirm director approval, keep filing evidence and make sure the same figures can support HMRC, Companies House, shareholders and the accountant.
A useful review note should answer three questions: what source evidence was used, what judgement was applied, and who approved the treatment. Keep that note beside the transaction or period report rather than in a separate inbox.
Common mistakes
- Tagging a draft trial balance
- Letting accounts and CT600 use different profit figures
- Saving only the PDF and losing the tagged file
The best prevention is a short, repeated checklist. If a control is too complicated to run every month or quarter, it will probably fail when the deadline is close.
How ReAI helps
ReAI supports the handover from bookkeeping to accounts production by keeping reconciliations, journals and review evidence together. That reduces the need to rebuild annual accounts from disconnected exports. For hands-on help with setup, see Accounting Assistance for Small Businesses .
Summary
Treat iXBRL tagging for small company accounts as a recurring accounting control, not a one-off admin task. Put the source data, review owner, exception list and submission evidence in the same system before the deadline arrives. That makes compliance work easier to check and much less dependent on memory.