If you are a director who has historically filed your own company accounts and tax returns using the free joint service on GOV.UK, it is time to prepare for a change. HMRC and Companies House have confirmed that this joint filing portal—often called the "CATO" service—will close permanently on 31 March 2026.
This is a major step in the government’s plan to modernise the UK’s digital infrastructure. From 1 April 2026, all companies must use commercial software to file their Corporation Tax returns.
What This Means for DIY Directors
The closure of the free portal means that the era of simply typing figures into a web form is ending. To remain compliant, you will now need to use HMRC-recognised software that can "tag" your data correctly for digital processing. While Companies House has paused its own move to software-only filing for the time being, the fact that your tax return now requires software makes a fully integrated digital approach the only sensible way forward.
Don't Lose Your History
A critical warning for all business owners: once the portal closes in March 2026, you will no longer be able to access your past returns through that system. We strongly advise all clients to download and save at least the last three years of filed accounts and tax returns before the deadline.
How CoreAcc Accountants Can Help
At CoreAcc Accountants, we already use the high-level software required for these new mandates. We can take the stress out of this transition by:
● Moving your records onto a compliant digital platform.
● Handling the complex "iXBRL" tagging required for HMRC submissions.
● Ensuring your historic data is safely backed up and accessible.
