From 1 April 2026, the way companies file their Corporation Tax returns and annual accounts is changing.

HMRC and Companies House are retiring their free online filing service. That means, from April 2026, you’ll need to use commercial software—like Tax Optimiser—to submit your returns.

Here’s what’s changing, why it matters, and what you need to do now to stay ahead.

Why is the current service closing?

HMRC built the current service to help small businesses with simple tax affairs. But over time, it’s fallen behind modern digital standards—and recent changes to UK company law mean it’s no longer fit for purpose.

Instead, HMRC and Companies House want to encourage the use of commercial tools that offer:

• Better validation (fewer errors)

• More support and guidance

• Automated reminders (so you don’t miss a thing)

Companies House is also rolling out new security measures like Identity Verification as part of the Economic Crime and Corporate Transparency Act. That means changes are coming for how all companies file.

What happens before 31 March 2026?

If you’ve been using HMRC’s free online service, make sure you save your records before it shuts down. After 31 March 2026, you won’t be able to access past submissions online.

We recommend downloading at least three years of returns and accounts—especially if you:

• Expect to hire an accountant or agent later

• Might need to refer back during a compliance check

• Want to keep complete records just in case

How to download your past submissions:

1. Go to the track your submissions page.

2. Pick the tax year you want to save.

3. Click either the HMRC or Companies House link.

4. On the summary page, choose ‘save your return in HTML’.

5. Save the file to your computer.

Simple. But don’t leave it to the last minute.

What if you need to amend something later?

After the service closes, you’ve got three options if you need to fix or re-file:

1. Use commercial software (like Tax Optimiser).

2. File by post to HMRC.

3. Ask an agent to handle it for you.

To fix your accounts with Companies House, you’ll need software or paper forms.

That’s more admin than most of us want. So getting the right software in place early is a smart move.

Filing from 1 April 2026: What you’ll need

From April 2026, software will be the default way to submit Corporation Tax returns and annual accounts. That includes:

• CT600 forms

• Your Corporation Tax computation

• iXBRL-tagged accounts (for most companies)

Tax Optimiser handles all of this in one place—and makes sure everything’s fully compliant with HMRC and Companies House requirements.

We’ve built it to make tax easy, whether you’re a small company doing it yourself or a growing business with bigger plans.

Some groups—like dormant charities or flat management companies—might qualify for an exemption from filing Corporation Tax. But if you're active and trading, the rule is simple: you’ll need software.

A quick recap

✅ Free HMRC service closes 31 March 2026
✅ Save old returns before then
✅ Use commercial software (like Tax Optimiser) from 1 April 2026
✅ Stay compliant, avoid penalties, and keep it stress-free

Why choose Tax Optimiser?

We’re not just ticking boxes. With Tax Optimiser, you get:

• Straightforward tax return and accounts filing

• Automatic checks before you file

• Friendly support when you need it

• A simple interface built with real businesses in mind

Make the switch now and get ahead of the deadline. You’ll thank yourself next April.