Previous joint-service users now need a replacement Corporation Tax filing workflow.
Preserve old records, select software that covers the complete return package, configure authority access and test before the next deadline.
Closure date and replacement route
The joint online service for company accounts and Company Tax Returns closed on 31 March 2026. HMRC says users should use commercial software from 1 April 2026 to file Company Tax Returns.
Preserve historical evidence
If it has not already been done, retain the records available from the previous service and existing company files.
- Filed accounts and computations
- CT600 returns and supplementary pages
- Submission references and authority responses
- Payment records
- Correspondence, amendments and rejection notes
Select software by coverage
Confirm that the chosen product can create the CT600, computation and accounts elements the company needs. Check supplementary pages, amendments, iXBRL generation or import, Companies House filing and support for rejected submissions.
Configure a controlled replacement workflow
Complete setup before the deadline period.
- HMRC agent or company authorisation
- Companies House authentication and presenter credentials where used
- Company and accounting-period data
- User roles and reviewer access
- Test return or validation workflow
- Evidence retention and export
Where professional judgement is needed
This guide explains a filing workflow, not the accounting treatment, tax position or legal duties of a particular company. Confirm the applicable accounting framework, reliefs, disclosures and filing obligations against current official guidance and, where needed, a qualified accountant or tax adviser.
FAQ
When did the joint service close?
It closed on 31 March 2026.
What is the HMRC route now?
HMRC directs users to commercial software for online Company Tax Return filing.
Can Companies House accounts still have a separate filing route before 2028?
Yes. The Companies House accounts route is separate, although software-only accounts filing is announced for filings from 1 April 2028.
What records should be retained?
Keep the exact returns, accounts, computations, submission references, responses, payments, amendments and review evidence.
Official sources
Checked on 2026-08-11. Official guidance takes priority if rules change.