HMRC’s Free Corporation Tax Filing Has Closed: What to Do Now
If you’re a small company director who’s always filed your own Corporation Tax return for free through HMRC, that option no longer exists. HMRC permanently closed its free joint filing service on 31 March 2026, and thousands of small companies still haven’t switched to a proper alternative. This guide from Filing Accounts UK explains what closed, who’s affected, and exactly what to do now, using only verified facts from official HMRC and Companies House guidance.
At Filing Accounts, we file CT600 returns and annual accounts for UK small businesses using HMRC-recognised commercial software.
What Actually Closed
The service that closed is known as CATO u2014 Company Accounts and Tax Online u2014 a joint HMRC and Companies House portal, running since 2011, that let smaller companies with straightforward affairs file their Company Tax Return and statutory accounts together, for free, in one place.
HMRC’s stated reason: the platform, now over a decade old, no longer meets modern digital standards or aligns with reforms introduced under the Economic Crime and Corporate Transparency Act.
What This Means in Practice
- CT600 filing with HMRC now requires HMRC-recognised commercial software u2014 there’s no longer a free government portal for this, except in very narrow “reasonable excuse” cases where paper filing may still be permitted.
- Annual accounts with Companies House can still be filed via Companies House WebFiling or paper, for now u2014 that side of things hasn’t closed, though Companies House has separately signalled a move toward software-only accounts filing from April 2027.
- Historic returns filed through the old CATO system are no longer accessible online at all u2014 if you didn’t download copies before the closure, you may need to request them directly from HMRC or Companies House instead.
If you already use an accountant, this change likely happened behind the scenes without you noticing u2014 most accountants were already using commercial software rather than the free portal. The real impact falls on directors who were self-filing using the free service.
What You Should Do Now
1. Check Whether You’re Actually Affected
If an accountant already files your CT600, confirm with them that they have a system in place u2014 most will, but it’s worth asking rather than assuming.
2. Retrieve Historic Filings if You Haven’t Already
If you relied on CATO and didn’t download your past returns before it closed, contact HMRC directly to ask about accessing historic records u2014 don’t assume they’re permanently lost without checking.
3. Choose a Filing Route Before Your Next Deadline
You have two realistic options: HMRC-recognised commercial software, or an accountant who files on your behalf. GOV.UK maintains a list of recognised commercial software suppliers for Corporation Tax. There’s no need to formally notify HMRC or Companies House of your choice u2014 you can simply start using new software or an agent ahead of your next filing deadline.
4. Don’t Leave It Until Your Deadline Is Close
Switching systems takes a little time to get comfortable with, particularly if you’re used to a simple government form. Sort this out well ahead of your CT600 filing deadline, not in the final week.
Does This Affect Dormant Companies Too?
Yes, in the same way. Even a company with no trading activity still has ongoing filing duties with Companies House, and if HMRC has issued a notice to deliver a CT600, that must now go through commercial software too. See our guide on whether dormant companies need to file a CT600 for the specifics.
What’s Unaffected
- Your actual Corporation Tax deadlines haven’t changed u2014 still 9 months and 1 day for payment, 12 months for filing
- Your Companies House accounts filing route is unaffected for now u2014 WebFiling and paper remain available
- Late filing penalties work exactly as before u2014 the closure doesn’t create any grace period
Common Mistakes to Avoid
Assuming Your Accountant Automatically Has This Covered
Most do, but it’s a quick, worthwhile question to confirm rather than assume, especially if you’ve recently switched accountants or use a smaller practice.
Waiting Until the Deadline to Sort Out New Software
Getting comfortable with new commercial software takes longer than expected the first time u2014 start well before your next filing is due.
Assuming Historic Returns Are Permanently Unrecoverable
The self-service portal is gone, but HMRC and Companies House may still be able to provide historic records on request u2014 worth asking before assuming they’re lost.
Frequently Asked Questions
Has HMRC’s free Corporation Tax filing service really closed?
Yes. The joint HMRC/Companies House CATO service closed permanently on 31 March 2026.
Do I need to tell HMRC I’m switching to commercial software?
No formal notification is required u2014 you can simply start using new software or an accountant ahead of your next filing deadline.
Can I still file my Companies House accounts for free?
Yes, for now, via WebFiling or paper u2014 it’s the HMRC side (CT600 filing) that now requires commercial software, not the Companies House accounts side.
What if I need an old tax return I filed through the free service?
Contact HMRC directly u2014 the self-service access is gone, but records may still be obtainable on request.
Need a New Way to File Your CT600? Talk to Filing Accounts UK
At Filing Accounts, we already file CT600 returns and annual accounts using HMRC-recognised commercial software u2014 so if you’re one of the many small companies now needing a new filing route, we can take it off your hands entirely.
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