The change affects the filing route, not the underlying responsibility. Companies and their agents need software capable of producing and submitting the required Corporation Tax package.
What the software needs to handle
HMRC advises users to check whether the chosen software can file the elements they need, including:
- the CT600 Company Tax Return;
- the Corporation Tax computation; and
- the company accounts in the required format.
Paper returns are accepted only in limited circumstances. A normal filing workflow should therefore assume software submission.
The deadlines remain separate
The Company Tax Return is normally due 12 months after the end of the accounting period. Corporation Tax is usually payable earlier—9 months and 1 day after the accounting period ends for companies outside the quarterly-instalment regime.
What practices should check
- Confirm that the chosen product supports the required CT600, computation and accounts filing.
- Update engagement letters and client instructions that still refer to the old online service.
- Build software setup and authorisation into new-company onboarding.
- Keep the payment deadline separate from the return-filing deadline.
- Allow time to resolve rejected submissions before the statutory deadline.
A correct tax computation is not enough if the practice has not confirmed how the complete return package will reach HMRC.
This article is general information, not UK tax, accounting or legal advice. Check the linked official guidance and obtain advice for the relevant facts.