Free HMRC company tax return filing ends on 31 March

Sara White, Editor, Business & Accountancy Daily. Croner-i

All businesses will have to use commercial software to file company tax returns from 1 April as current system ‘outdated’ but warning to save three years of records.

Companies House and HMRC are closing the joint online filing service on 31 March 2026 removing the free option completely. This will remove all records held in the online filing service so it is essential to make backups as a matter of urgency.

From 1 April 2026 companies will have to use software to file company tax returns with HMRC rather than the old free system, although they will be able to continue to file annual accounts at Companies House using third party software, WebFiling services or paper filing.

Companies House said: ‘The service is closing because it’s outdated and no longer aligns with modern digital standards, enhanced corporation tax requirements or changes to UK company law under the Economic Crime and Corporate Transparency Act’.

Before the system closes for good on Tuesday 31 March, Companies House recommends ‘downloading and saving at least three years of accounts filings for your company. You will not be able to access any previous filings on this service after 1 April 2026’.

It is important to note that as soon as the free filing service closes, company directors needing to make changes to a previous submitted corporation tax return, or re-file a rejected return will have to use commercial software.

Critically, the financial information previously filed will no longer be available in the system as it will not be stored anywhere and will have to be re-entered again.

Previous years filed company tax returns can only be be downloaded using the HMRC online service by going to the ‘track your submissions’ page and selecting the period of the return required, then saving the file in HTML.

For amendments, it is also acceptable to send a paper return to the Corporation Tax Services office, HMRC BX9 1AX, address or ask your accountant to deal with this.

Changes or corrections to financial accounts previously filed with Companies House, will have to be submitted using software or by sending paper accounts by post. You can file a paper return with HMRC if you have a reasonable excuse or want to file in Welsh. Otherwise, you must file online.

There are a few exceptions, for example if a company wants to file their tax return in Welsh or can provide a ‘reasonable excuse’ to HMRC, although this is very limited.

Companies House said: ‘This future change supports our goal of enabling a fully digital filing service. It will also help us to meet our organisational priority to prevent economic crime and bring the UK in line with international best practice.’

The closure of the corporation tax return free filing service comes after a major breach of IT security at Companies House, first identified on 13 March, which saw the WebFiling system exposed to potential attacks as logged-in registered users ‘could potentially access and change another company’s details without their consent after performing a set of specific actions’. 

An investigation found the IT breach actually started last October when Companies House adopted the government’s new single sign on service, Gov.uk One Login, replacing Government Gateway accounts completely. It has now been resolved and the system has been secured to avoid any repetition, Companies House stressed.

This raised immediate concerns about the security and reliability of Gov.uk One Login, which the government is rolling out across multiple departments, in time replacing the entire Government Gateway system.

This is particularly relevant as HMRC is currently rolling out Gov.uk One Login to individual taxpayers, but is only at the early stages with new users required to use the new system, while existing Gateway account holders continue as normal for now.

When questioned about the security of the system, HMRC told Business & Accountancy Daily: ‘The Companies House web filing service is independent of HMRC systems, so our systems remain secure.’