For more than a decade, small companies relied on the HMRC free online filing service to submit their accounts and Corporation Tax returns without paying for software. That option is gone: it closed permanently on 31 March 2026, and every company that used it now needs another way to file.
This guide covers what the HMRC free online filing service did, why it closed, and what UK businesses need to do next, including a look at Corporation Tax UK obligations, Corporation Tax software, and cloud accounting. If the change feels daunting, a professional such as Top Bookkeeping Services can manage the switch for you and keep your filings on track.
What Was the HMRC Free Online Filing Service?
Officially known as Company Accounts and Tax Online (CATO), this joint HMRC and Companies House tool launched in 2011 to give smaller companies a free, single route through two separate legal obligations.
How the Service Worked
Users entered their figures once, and the service produced both a CT600 Corporation Tax return and a set of statutory accounts, automatically converting the accounts into the iXBRL format HMRC requires.
Who Used It
It was aimed at small, unrepresented companies with straightforward affairs, typically micro-entities, contractors, and directors who preferred to file their own paperwork rather than pay for software or an accountant.
What Businesses Could File
Users could submit a Company Tax Return, full or abbreviated statutory accounts, and dormant company accounts, all through one free portal.
Why Did HMRC Close Its Free Filing Service?
Reasons for the Closure: HMRC said the old system was no longer suitable for modern digital requirements. Changes in UK company law, including new identity-checking rules and updated accounts formats, also made it necessary to move to a newer filing system.
Move Towards Commercial Filing Software: Instead of updating the free service, HMRC chose to rely on commercial software. There are now many affordable options available, including software suitable for small businesses.
What the Change Means for UK Businesses: Businesses that previously used the HMRC service now need another way to file their returns. Companies that already use an accountant may see little change, while businesses that file their own returns will need to choose and set up suitable software.
When Did the HMRC Free Online Filing Service Close?
The HMRC free online filing service closed permanently on 31 March 2026. After this date, businesses can no longer use the old portal to submit new Company Tax Returns, and Businesses should make sure they retain copies of previous returns and accounts, rather than relying on the closed service for future access.
What Changed From 1 April 2026
From 1 April 2026, companies need to use HMRC-recognised commercial software to file their Company Tax Returns. Companies House accounts can still be filed through WebFiling, paper, or third-party software, although Companies House is also moving to mandatory software filing for annual accounts, with the change currently scheduled for 1 April 2028.
Which Businesses Are Affected?
The change affects any company that previously used the joint service to file its own returns. This includes dormant companies, micro-entities, one-person limited companies, and other small businesses that relied on the free HMRC filing service.
What Do UK Businesses Need to Do Instead?
With the HMRC free online filing service no longer available, businesses need to switch to a suitable filing method and make sure their Corporation Tax records are ready.
- Choose Corporation Tax Filing Software: Select HMRC-recognised software that can prepare and submit your CT600 and, ideally, support iXBRL accounts.
- Prepare Your Company Accounts: Prepare your statutory accounts, including the balance sheet, profit and loss account, and required notes.
- Prepare Your Corporation Tax Computation: Adjust your accounting profit for tax purposes, including relevant reliefs and allowances, to calculate your taxable profit.
- Complete and Submit Your CT600: Complete your Company Tax Return and submit it electronically through your chosen commercial software.
- Keep Your Tax Records: Keep digital copies of your tax returns and accounts, including previous filings, for future reference.
Corporation Tax UK: What Businesses Need to Know
Corporation Tax UK is charged on the taxable profits of limited companies, clubs, and other unincorporated bodies, covering trading profits, investment income, and gains on asset sales. UK companies may need to file a Company Tax Return if HMRC issues a notice to deliver one. A company may still need to file a return even if it has made a loss or has no Corporation Tax to pay.
Every active company must file a Company Tax Return each accounting period, along with statutory accounts, whether or not tax is owed. The CT600 is normally due 12 months after the accounting period ends, while payment is due earlier nine months and one day after the period ends for most small and medium companies. Missing the deadline triggers automatic penalties, which increase for filing dates on or after 1 April 2026, making timely, compliant filing more important than ever.
Corporation Tax Software Filing UK Explained
Corporation Tax software filing UK tools are built to prepare and submit CT600 returns directly to HMRC, taking over the role the old free portal used to play. Most walk you through turnover, expenses, allowances, and reliefs, then build the tax computation automatically, reducing the risk of manual errors.
For companies whose accounts need to be submitted in iXBRL format, choosing software that can prepare and tag the accounts correctly is important. This was one of the quiet strengths of the free service that businesses now need to replace. When choosing a package, look for one on HMRC’s recognised list that covers both the CT600 and accounts if needed, and matches your company’s complexity: a micro-entity has very different needs from a group with several subsidiaries.
Can Cloud Accounting in the UK Help With Corporation Tax?
Cloud accounting can make the transition easier by keeping bookkeeping records, bank transactions and financial data organised. However, ordinary cloud bookkeeping software does not necessarily file a Company Tax Return with HMRC.
Before choosing software, check that it supports the Corporation Tax filing requirements your company needs and, where applicable, can integrate with your accounting system.
HMRC Free Filing Service vs Commercial Software
| Feature | Old HMRC Service | Commercial Software |
| Cost | Free | Paid — subscription or per-return |
| Corporation Tax filing | Simple cases only | Simple and complex cases |
| CT600 | Included | Included, often with guided prompts |
| Accounts filing | Included (joint service) | Varies by provider |
| iXBRL | Automatic | Automatic in most modern tools |
| Cloud functionality | None | Often cloud-based |
The old service was never designed to scale with growing or complex businesses, which is part of why commercial alternatives have taken over.
What Are the Alternatives to the HMRC Free Filing Service?
Commercial Corporation Tax Software
Dozens of HMRC-recognised providers now offer CT600 filing, from simple pay-per-return tools to full platforms for accountants managing many clients.
Cloud Accounting Software
It can handle bookkeeping and, with the right integration, link directly to a Corporation Tax filing module, streamlining the process from transaction to submission.
Using an Accountant
Many owners are using this change as a reason to hand filing to a professional, who can manage accounts, computations, and CT600 submission without you needing to learn new software.
Paper Filing in Limited Circumstances
Paper filing is only available in limited circumstances, including where a company has a reasonable excuse or is filing in Welsh. Specific legal exemptions can also apply in certain circumstances.
How Much Does Corporation Tax Software Cost in the UK?
A handful of providers still offer free filing for the simplest dormant or nil-return cases, but most active companies need a paid product. Many charge an annual subscription, useful for businesses filing every year and wanting ongoing support; others charge a flat fee per return, which suits a company filing only once a year. Software is usually cheaper upfront than an accountant, but it takes your own time and confidence to use it well for businesses with more complex affairs; professional support can be worth the extra cost.
Who Is Most Affected by the HMRC Filing Service Closure?
Small limited companies that previously filed everything themselves now face a real decision: learn new software or outsource the task. Micro-entities are usually well served by low-cost commercial tools but still need to make the switch. One-person companies and contractors running their own limited company may be filing and paying for software for the first time. Start-ups should build the cost of Corporation Tax software, or of Top Bookkeeping services, into their budget from day one. Anyone who has always filed their own tax return should treat this as the moment to invest in suitable software or move to a trusted adviser.
Common Mistakes Businesses Should Avoid
- Assuming the old HMRC service is still available. The HMRC free online filing service is gone, not paused; don’t risk missing a deadline by assuming otherwise.
- Choosing unsuitable software. Not every product handles both the CT600 and accounts, or every level of company complexity.
- Missing filing deadlines. Penalties increased from 1 April 2026, so set reminders well ahead of time.
- Confusing HMRC and Companies House filing. These remain two separate obligations; filing with one doesn’t satisfy the other.
- Not keeping previous records. Old filings are no longer accessible through the closed portal.
- Waiting until the deadline to set up software. Early preparation avoids unnecessary pressure and mistakes.
Conclusion:
The closure of the HMRC free online filing service on 31 March 2026 is a genuine turning point for small UK companies. A simple, free route to meeting your filing obligations has been replaced by a market of commercial software providers, each with different features, prices, and support.
The good news is there’s a solution for almost every size of company, from low-cost, pay-per-return Corporation Tax software filing UK tools to fully integrated platforms linked to cloud accounting. What matters is choosing software that fits your company’s complexity, keeping your historic records safe, and not leaving the switch until the last minute.
If you’d rather not manage the transition yourself, professional Top Bookkeeping services can handle accounts preparation, tax computations, and CT600 submission on your behalf, leaving you free to run your business while staying fully compliant ahead of every deadline.
Need Help With Corporation Tax Filing?
If the closure of the HMRC free filing service has left you unsure which software to use or how to manage your company’s next return, Top Bookkeeping Services can take care of the process for you. From bookkeeping and statutory accounts to Corporation Tax computations and CT600 submission, our team can help keep your business compliant without the hassle of learning new filing software.
Get in touch with Top Bookkeeping Services today to discuss your Corporation Tax filing requirements.
Frequently Asked Questions
Is the HMRC Free Online Filing Service Still Available?
No. It closed permanently on 31 March 2026 and can’t be used to file new returns or access old ones.
How Do I File My Corporation Tax Return Now the Old Free Service Has Closed?
You need HMRC-recognised commercial software, or an accountant using such software, to prepare and submit your CT600 from 1 April 2026 onwards.
Do I Need to Buy Corporation Tax Software to File My Tax Return?
In almost all cases, yes. Paper filing is only permitted in very limited circumstances with prior HMRC approval.
Can I Use Cloud Accounting Software to File My Corporation Tax Return?
Cloud accounting in the UK helps keep your records organised, but you’ll usually still need a dedicated Corporation Tax filing module to actually submit the CT600.
What Happens if I Cannot File My Corporation Tax Return Using Commercial Software?
Ask HMRC about limited exemptions, or engage an accountant or bookkeeping provider who already holds suitable software and can file on your behalf.