What actually changed on 31 March 2026?
For years, small companies could file their annual accounts and Company Tax Return through a free online service run jointly by HMRC and Companies House. That service has closed. It shut on 31 March 2026, and gov.uk now says plainly: "The service to file your accounts and Company Tax Return has closed."
(Our guide on what happened to HMRC's free filing service has the full story.)
From 1 April 2026, the official guidance is to use commercial software to file your Company Tax Return with HMRC. Paper filing is only allowed in narrow cases, such as having a reasonable excuse or filing in Welsh. Your accounts still go to Companies House every year as well, through software or the routes Companies House itself offers.
Notice what is missing from that list of changes: nothing about who is allowed to file. The rule was, and remains, that the return must be filed. Who prepares it is up to you.
Is it still legal to file without an accountant?
Yes, completely. HMRC's own page on Company Tax Returns lists two equal options: prepare and file the return yourself, or get an accountant to do it for you. That page is live today, after the closure. Self-filing is not a loophole or a grey area. It is one of the two routes HMRC itself describes.
The obligations have not changed either. Your company must file a Company Tax Return when HMRC sends it a notice to deliver one, even if the company made a loss or owes no tax. The return is due 12 months after the end of the accounting period it covers, and any Corporation Tax is due earlier, 9 months and 1 day after the period ends. All of that is the same whether an accountant files or you do. The only new ingredient is the software.
Who is self-filing right for?
Self-filing suits the kind of company the free service was built for: a small, simple business where the director already knows the numbers. You are likely a good fit if:
- Your company is small, for example a micro-entity: broadly, turnover of £1 million or less, a balance sheet of £500,000 or less, and 10 or fewer employees, meeting two of the three (limits for accounting years beginning on or after 6 April 2025).
- Its income and costs are straightforward: sales in, normal running costs out.
- It is a single company, not part of a group.
- You filed it yourself quite happily before the free service closed.
If that is you, the closure changed your tool, not your ability. The judgement calls you made on the free service, like what counts as a business cost, are the same judgement calls in commercial software.
Who should honestly use an accountant instead?
Some companies should not self-file, and it would be dishonest of us to pretend otherwise. An accountant is genuinely the right answer if any of these apply:
- Your company is part of a group, or over the small-company size limits.
- You are claiming complex reliefs, for example research and development claims.
- The year included something unusual and significant: buying or selling a business, property deals, large one-off items you are unsure how to treat.
- The company's affairs are in a mess, for example years of missed filings.
This is not about intelligence. It is about risk. Paying a professional for a complex year is often the cheapest option available.
What do I need to self-file in 2026?
Here is the reassuring part: the list is the same one you already know. Three things identify you and your company:
- Your company's UTR. The 10-digit tax reference HMRC gave your company. It is on letters from HMRC, such as the notice to file. If you cannot find it, your company can request a copy online and HMRC posts it to the business address registered with Companies House.
- Your Government Gateway sign-in. The user ID (up to 12 characters) and password you use for HMRC online services, with Corporation Tax set up in the account. The same sign-in you used for the free service.
- Your Companies House authentication code, for filing the accounts. A 6-character code that acts as the online equivalent of a director's signature. If you have lost it, request it through Companies House; it arrives by post at your registered office and can take up to 10 working days, so do not leave that to deadline week.
Then you pick a piece of commercial software, enter the same figures you always did, check them, and file. The software turns your figures into the technical format HMRC requires and sends them through the official channels.
What does "HMRC-recognised software" mean?
To help people choose their software, HMRC publishes a directory of commercial software suppliers for Corporation Tax filing. Its own wording is simple: HMRC accepts returns filed using any of the products shown in that document. In other words, recognition means the supplier has shown HMRC its product can file returns in the right format through the right channel. The list is a directory that helps you shop, not a licence you need before you are allowed to file.
One honest caveat: a place on that list is about technical filing capability, not HMRC reviewing a product's helpfulness or recommending it over another. You still choose the product that suits you. Our guide on what HMRC-recognised software actually means goes deeper.
What happens if I just do nothing?
Doing nothing is the one option that genuinely got more expensive this year. From 1 April 2026, filing a Company Tax Return late costs £200 on the very first day (doubled from the old £100), a further £200 if you are 3 months late, and up to £2,000 for repeat offenders. That applies even if your company is dormant, made a loss, or owes no tax. Companies House charges its own separate penalties for late accounts, up to £1,500 for a private company. So the real risk is not "I am no longer allowed to file". It is waiting so long to pick a new tool that the deadline arrives first.