If you run a small limited company and you have always filed your accounts and tax return through HMRC's free online service, that option has gone. The service closed on 31 March 2026, and there is no free HMRC replacement for your Company Tax Return.
TL;DR: HMRC's free joint service for filing company accounts and the Company Tax Return closed on 31 March 2026. From 1 April 2026 you must use commercial software to file your CT600 with HMRC. You can still file accounts with Companies House online or on paper. Small companies that filed themselves are most affected.
What Exactly Closed on 31 March 2026?
HMRC's free "File your accounts and Company Tax Return" service, which many small directors knew as CATO, closed permanently on 31 March 2026 (GOV.UK, 2026). It let you send your annual accounts to Companies House and your Corporation Tax return to HMRC in one online transaction, at no cost.
The service was only ever open to small, unrepresented companies with simple affairs, typically owner-managed businesses filing without an accountant (RSM UK, 2026). HMRC has said it closed because it no longer met modern digital standards or the enhanced Corporation Tax and company law requirements brought in by the Economic Crime and Corporate Transparency Act. Nothing replaces it as a free HMRC route.
Do You Still Need Software to File Your Accounts?
Not necessarily. The change is narrower than a lot of the coverage suggests. You can still file your annual accounts with Companies House using its own online service or by sending paper accounts by post (GOV.UK, 2026). What has gone is the free HMRC route for your Company Tax Return.
So the split is the thing to hold onto. Accounts to Companies House: web service, paper, or software all remain options for now. Company Tax Return to HMRC: commercial software only. In our experience, this is the point that catches directors out. They assume the whole job now needs a paid package, when only the tax return half has changed. A separate reform will move Companies House accounts to software-only filing from April 2028, which we cover in our guide to the 2028 changes.
How Do You File Your Company Tax Return Now?
You file it using HMRC-recognised commercial software. The CT600 must be submitted online with your accounts tagged in iXBRL format, and paper returns are only accepted where you have a reasonable excuse or you file in Welsh (GOV.UK, 2026).
You have two practical routes. Buy accounts and tax software and file it yourself, or appoint an accountant who files on your behalf through their own software. Some packages let you submit the accounts and the Company Tax Return together, which keeps the one-step feel of the old service. What we see most often is directors of dormant or very small companies leaving this too late, then reaching a filing deadline with no tool in place and no time to test one.
Which Software Is HMRC-Recognised?
HMRC publishes a list of recognised commercial software suppliers for Corporation Tax, and only software on that list can file a valid CT600 (GOV.UK, 2026). Named suppliers include Sage, IRIS, Thomson Reuters, FreeAgent and Xero Tax, alongside many others.
HMRC does not endorse any single product, so the right fit depends on your company. If you want to replicate the old free service, look for a supplier that files the return and the accounts together. Costs vary widely, from tools bundled with business software you may already pay for, to standalone filing packages. One question clients always ask is whether they can keep filing on paper. For the tax return, the answer is generally no.
Accessing Your Old Returns After the Closure
No. Once the service closed, you lost the ability to view or amend returns you had previously submitted through it. HMRC advised users to download and save at least the last three years of filed returns before 31 March 2026 (ATT, 2026).
If you missed that window, your filed accounts are still on the public register at Companies House, so those you can retrieve at any time. For copies of Corporation Tax returns held only in the old service, you will need to contact HMRC directly. This matters if you are applying for finance or need prior-year figures to prepare this year's return.
What Happens If You Miss the Filing Deadline?
Both Companies House and HMRC charge for late filing. Companies House penalties for a private company run from £150 for accounts up to a month late to £1,500 for more than six months, and the penalty doubles if you file late two years in a row (GOV.UK, 2026).
HMRC adds its own Corporation Tax penalties, starting at £100 the day after the deadline and rising with further fixed and tax-geared charges the longer a return stays outstanding, which we set out in our breakdown of Corporation Tax late filing penalties. Your deadlines have not changed: accounts are due at Companies House nine months after your year-end, and the CT600 is due twelve months after the end of your accounting period, with the tax payable nine months and one day after period end.
Your Next Steps Before the Filing Deadline
Check when your next accounts and Company Tax Return are due, then decide how you will file before that date arrives. If you filed yourself through the old service, you need a plan now, not in the final week before the deadline.
Pick recognised software and test it well ahead of time, or hand the filing to an accountant who can take on both halves. If you run more than one company, or your accounts include anything beyond the simplest figures, professional filing usually costs less than a missed deadline. It is also worth checking your director identity verification is in order, since Companies House ID checks are being enforced under the same ECCTA reforms. For the wider picture, our year-end accounts checklist runs through what to prepare.
Frequently Asked Questions
Was the closed service the same as CATO?
Yes. The "File your accounts and Company Tax Return" service was commonly called CATO, short for Company Accounts and Tax Online. It closed on 31 March 2026 and has no free HMRC replacement.
Can I still file my accounts on paper?
Yes, for now. You can send paper accounts to Companies House by post, or file them through the Companies House online service. Only your Company Tax Return to HMRC must go through commercial software. Companies House accounts move to software-only filing from April 2028.
Do dormant companies still have to use software for the tax return?
If HMRC has issued a notice to deliver a Company Tax Return, a dormant company files it the same way, through recognised commercial software. Many low-cost packages handle dormant and micro-entity returns. Check whether HMRC still expects a return before you file.
Is there any free software to replace the old service?
HMRC no longer provides a free filing tool. Some commercial products are low-cost, and a few business software subscriptions include filing, but there is no direct free HMRC equivalent. Compare suppliers on the HMRC recognised list before you buy.
What if I already missed a deadline because of the change?
File as soon as you can to stop penalties building, then appeal if you have a reasonable excuse. Companies House and HMRC both consider appeals, but not knowing the service had closed is unlikely to succeed on its own. Get the filing done first.
If your company filed through the old HMRC service and you are not sure what to do before your next deadline, get in touch. We file accounts and Company Tax Returns for small UK companies every week and can take both halves off your plate.