HMRC Free Filing Service Has Closed: What Small Businesses Need to Do

On 31 March 2026, HMRC and Companies House permanently closed their joint online filing service. If your company relied on it, here is what you need to do next.

The end of HMRC's free company tax filing service

Many small companies knew it simply as the HMRC online filing service or CATO (Company Accounts and Tax Online). For years, it allowed small limited companies to file annual accounts, Corporation Tax returns (CT600), and supporting accounts information in one go, without needing commercial software or an accountant.

From 1 April 2026, that option no longer exists. If your company previously relied on the service, you now need a different way to file your accounts and Corporation Tax return.

Why did HMRC close CATO?

According to HMRC and Companies House, the service no longer met modern digital standards and could not support recent changes to company law and corporation tax reporting requirements.

The closure is also linked to wider reforms being introduced under the Economic Crime and Corporate Transparency Act. These reforms are changing how company information is filed and verified across the UK.

Who is affected?

The closure mainly affects:

• Small limited companies
• Micro-entities
• Dormant companies
• Directors who file their own accounts
• Businesses without an accountant

If you previously logged into GOV.UK and submitted your CT600 yourself, you are affected.

What do you need to do now?

1. Find software for future filings

Corporation Tax returns must now be filed using commercial software. The software must be capable of producing:

• A CT600 Corporation Tax return
• iXBRL tagged accounts
• Electronic submissions to HMRC

2. Check your filing deadlines

The closure does not change your filing obligations. You must still:

• File accounts with Companies House
• File a Corporation Tax return with HMRC
• Pay Corporation Tax on time

Missing a deadline can still result in penalties.

3. Keep copies of previous filings

Before the service closed, HMRC advised companies to download and save at least three years of historic filings. If you previously relied on the online service, make sure you have copies of your accounts, CT600 returns, and submission receipts for your records.

Do I need an accountant?

Not necessarily. Many small companies have straightforward accounts and continue to file without an accountant. The key difference is that you now need software capable of creating and submitting the required documents.

For more complex situations, such as group companies, investment businesses, research and development claims, or multiple accounting periods, professional advice may still be worthwhile.

What about dormant companies?

Dormant companies are also affected. While dormant company accounts can still be relatively simple, you may still need software if you need to submit a Corporation Tax return. The exact filing requirements depend on your company's circumstances and HMRC's expectations.

What happens next?

The closure of CATO is part of a broader move towards digital filing. Companies House has already announced further reforms that will require all companies to file accounts using commercial software from April 2028. For many businesses, moving to software now is likely to make that transition easier.

Looking for a simple filing option?

If your company is a micro-entity with straightforward accounts, software designed specifically for self-filing can often be more affordable and easier to use than a full accounting package. Accountable Filing is designed for small companies that want to prepare and file their accounts and Corporation Tax returns without needing a traditional accounting firm.