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Posted: Tue 6th Jan 2026
Last updated: Tue 6th Jan 2026
8 min read
From 31 March 2026, HMRC and Companies House will switch off their free joint online service for filing company accounts and Corporation Tax returns, often called the CATO portal.
After that date, you won't be able to use it or access historic returns through it.
From 1 April 2026, if you run a company, you'll need commercial software to file your Corporation Tax return (CT600) with HMRC.
There will be no free HMRC web form for companies, except in very narrow "reasonable excuse" cases where paper filing is allowed.
For many one-person and micro-companies that currently self-file for free, this is a real change. Here's what it means in practice and what you should do now.
For years, straightforward small and micro companies have been able to:
log in to the joint HMRC/Companies House portal
type figures into a simple web form
submit their CT600 and micro-entity or abridged accounts at the same time, for free
That service is being retired. The official line is that:
it no longer meets current digital standards
it doesn't fit with wider changes to company law and the Economic Crime and Corporate Transparency Act, which push towards tagged digital accounts and more detailed data from companies
From 1 April 2026:
Corporation Tax: All companies will have to file CT600s using HMRC-recognised commercial software.
Accounts to Companies House: For now, you can still use Companies House WebFiling or paper, as well as software.
However, Companies House has been working towards software-only accounts filing from April 2027, and is telling companies they'll need to move onto suitable software in due course.
Ministers have signalled they may scale back parts of that package after pushback from small business groups concerned about cost and disclosure.
What isn't in doubt is the 2026 decision – the free joint filing portal will close and Corporation Tax filing will move on to paid third-party software.
If you already pay an accountant to handle your company accounts and tax, you're unlikely to notice much difference.
Most firms already file using commercial software and will simply adjust behind the scenes.
The impact is sharpest for three groups:
DIY company directors: People who currently log in once a year, use the free HMRC form and don't pay for accounting software.
Very small or low-margin companies: Side-hustles, consultants, community interest companies and other micro-entities where a £50 to £150 yearly software fee is a noticeable hit.
Companies on the edge of compliance: Directors who only just manage to keep up with filing now. Extra friction or confusion makes missed deadlines and penalties more likely.
This change also sits in a wider trend. HMRC's Making Tax Digital programme already pushes landlords and sole traders towards third-party software, and critics have warned that the costs and complexity hit smaller taxpayers hardest.
If you're a director who currently does everything yourself, the shift has four practical effects:
A new fixed cost: Filing will no longer be free. You'll need either:
a simple CT filing tool that charges per return, or
an accounting package with CT600 filing built in, on a monthly subscription
Extra admin and learning curve: You'll have to choose a product, set it up and learn a new process.
More risk if you leave it late: If you try to pick software the week your filing is due, you're much more likely to run into problems, pay for the wrong thing or miss the deadline and incur penalties.
Less direct control over your data: Instead of dealing only with HMRC and Companies House, you'll depend on a private software provider's pricing and support.
If you run a company and currently use the free HMRC/Companies House service, there are some simple steps you can take over the next year.
Download your old returns and accounts: The government and professional bodies are telling companies to save at least the last three years of returns and accounts from the portal before it closes. You won't be able to access them online after March 2026.
Check whether you actually self-file: If an accountant already files on your behalf, they may already cover this change in their fees, though it is worth checking they have a plan for it.
If you self-file, start exploring options in 2025: Don't wait until your next deadline falls after April 2026. Look early at:
standalone CT600 tools aimed at small companies
entry-level accounting packages that include Corporation Tax filing
whether, for your situation, paying an accountant to do a compliance bundle every year is actually better value
Keep an eye on the Companies House side: The direction of travel is still towards tagged digital accounts filed through software, though ministers are now questioning how far and how fast to push small and micro companies.
Factor this in to your decision to stay incorporated: For some people running very small activities through a company, the extra fixed cost and admin might tip the balance towards operating as a sole trader instead.
Micro-companies and community organisations are now being asked to start paying private vendors simply to meet the same obligations they were already meeting for free, with no obvious improvement in service from their point of view.
Media coverage already shows small community groups weighing up fee hikes, organisational changes or closure because they can't justify the software cost.
That's why this matters. It's another example of "ticket to trade" costs creeping up for the very smallest entities.
We think HMRC should either keep a simple free online filing route for micro-entities or, at the very least, require recognised software providers to offer a genuinely free or token-cost "micro" tier, funded or mandated by government.
That means a one-person company with a basic return wouldn't be paying the same as a much larger business.
In the meantime, the main thing is to make sure directors aren't blindsided. If you run a small company and currently self-file, treat 31 March 2026 as a hard deadline.
Get your old records out, decide how you'll file in future and avoid a last-minute scramble that costs you more than it needs to.
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