HMRC’s Free CT600 Service Has Closed: What Small Company Directors Must Do Now

A practical guide for UK small company directors after HMRC closed its free Company Accounts and Tax Return service on 31 March 2026.

This article is written for Micro company directors who need a practical, filing-focused view of CT600, iXBRL tagging and HMRC submission requirements in the UK.

What changed in 2026?

HMRC’s free online service for filing company accounts and the Company Tax Return closed on 31 March 2026. From 1 April 2026, companies that previously relied on that route need commercial software or an assisted filing service. The tax return requirement has not gone away. The workflow has simply become more software-led, and for many micro-company directors that means more steps, more terminology and more room for avoidable errors.

Who is most affected?

The closure affects directors who previously handled everything themselves: micro-entities, owner-managed businesses, small trading companies, property SPVs and companies with straightforward but time-sensitive filings. These companies may not need a large advisory engagement, but they still need a properly prepared CT600, corporation tax computation and iXBRL-tagged accounts.

What you need before filing

Gather your final accounts, corporation tax computation, company UTR, accounting period, tax adjustments, details of losses or reliefs, and any supporting schedules. If accounts and computations do not agree, the filing package may fail review or require rework. Treat the CT600, accounts and computation as one connected filing package rather than three separate documents.

• Final accounts: approved numbers, not draft bookkeeping reports.
• Tax computation: clear adjustments and supporting schedules.
• Company details: UTR, accounting period and filing credentials.
• iXBRL files: accounts and computations prepared for digital submission.
• Submission evidence: confirmation receipts and final filed documents retained securely.

The new risk for DIY filers

The main risk is not that the company is complicated. The risk is that the filing package is incomplete, inconsistently prepared or not correctly tagged in iXBRL. A PDF may look correct, but HMRC systems need machine-readable data. This is where directors who are comfortable with bookkeeping can still struggle with digital filing.

Practical next step

Small company directors should decide early whether to buy software and learn the process, or use a filing service that prepares, tags, validates and submits the package. Leaving this decision until the filing deadline creates unnecessary penalty risk.

How Digital Reporting (UK) Helps

• Document intake and review: We check whether the accounts, computation and CT600 data are ready for filing.
• iXBRL tagging: We tag accounts and computations using a structured digital reporting workflow.
• Validation: We review the package for common technical and consistency errors before submission.
• Submission support: We help directors and firms move from source documents to a compliant filing package.