Hi

Here’s something you need to know well before it sneaks up on you: on 31 March 2026: the free online filing service for corporation tax returns provided by HMRC and Companies House will close for good.

If you’re a small business owner running a limited company, this matters. From that date, you (or your accountant) will need to submit your annual accounts and corporation tax returns using third-party commercial software.

Existing clients of Guilford Accounting won't be affected by the change as we already file your corporation tax return using commercial software.

But let’s break down what’s happening, why, and what you should be doing now to avoid last-minute headaches, if you (or your accountant) uses the free online filing service.

What’s Changing?

Since 2011, HMRC’s online system has let companies submit their company tax returns (CT600) and annual accounts to Companies House in one go. It automatically filled in most of the tax return, converted figures into the required iXBRL format, and made life easier for small companies filing online.

But the system is now being retired.

Why Is the Service Closing?

There are two big drivers:

• Outdated Technology – HMRC says the current system no longer meets modern digital standards.
• New Regulatory Requirements – The Economic Crime and Corporate Transparency Act has introduced stricter corporate governance and anti-fraud measures. This means Companies House is upgrading its systems, including identity verification and enhanced data checks.

Simply put, third-party software is better equipped to handle the new standards, avoid errors, and integrate with these upgraded systems.

Who’s Affected?

Any private limited company that files corporation tax returns is affected. If you have a year-end of 31 December 2025, you can still submit that tax return before 31 March 2026 using the old system. After that, you must use commercial software.

There are a few exceptions: charities, community amateur sports clubs, and dormant companies may qualify to file on paper – but you’ll need prior approval from HMRC.

What Should You Do Now?

If you’re working with an accountant, they’ll likely be ahead of this. But here’s what your business should be doing:

✅ Identify if You’re Affected
Do you or your accountant currently use the free HMRC service? If yes, you need to switch.

✅ Choose the Right Software
There’s a list of approved software providers on the HMRC website. Many cloud-based systems, like Sage for Accountants, handle both accounts and tax filings, making life easier.

✅ Get Ready Early
Don’t wait until March 2026. Start using the new software well ahead of time. Early adoption means fewer surprises.

✅ Save Your History
The HMRC system won’t store your old submissions forever. Download and save at least three years of past returns before the system shuts down. Go to the “track your submissions” page, pick the period, and save the return in HTML format.

How Will Filing Work Going Forward?

The good news is that modern accounting software is pretty slick. Here’s what it typically does:

• Pulls in your trial balance from bookkeeping systems like Xero or Sage.
• Validates your final figures.
• Creates accounts and tax computations in iXBRL format.
• Generates the CT600 tax return automatically.
• Flags any issues that need fixing before submission.

Once everything’s approved, it sends the submissions securely to both HMRC and Companies House. This is faster, more accurate, and reduces the risk of filing errors.

How Can Your Accountant Help?

Your accountant can:

• Help you select the right software if you want to handle filings yourself.
• Provide full-service online filing as part of their offering.
• Download and archive past filings from the HMRC system before it shuts down.
• Make sure you meet the new digital filing requirements and stay compliant.

A proactive accountant won’t just tell you what’s changing – they’ll guide you through the transition, recommend the best solutions, and set you up for smooth, hassle-free filings going forward.

This shift isn’t just about compliance. It’s a chance to upgrade your financial systems. Instead of seeing this as an annoying change forced on you, ask:

• Could better software improve my reporting accuracy?
• Could automation save time and reduce manual errors?
• Could integrated systems give me faster, clearer insight into how my business is performing?

By embracing these changes early, you’re not just staying compliant — you’re making your business more efficient, better informed, and ready for the future.

If you’d like, I can review your current filing setup or recommend software options tailored to your business needs. Let me know if you'd like to explore that?

Noel Guilford

PS Don't forget that that my new book Practice! has now been published and is available on Amazon; for a short time you’ll be able to grab a verified purchase copy for just £0.99.