When is corporation tax due UK?

Tax deadlines can feel like a moving target. Corporation tax, VAT, and now Making Tax Digital (MTD) each have their own due dates and rules. Missing a deadline can mean penalties and interest from HMRC. This article explains when corporation tax is due in the UK and how it fits with other key deadlines, including MTD for income tax. It is for limited company directors and small business owners who want to stay on top of their obligations.

We cover the main corporation tax deadlines, what you need to file, and how MTD is changing the landscape for sole traders and landlords. Knowing when things are due is the first step to staying compliant.

When is corporation tax due in the UK?

For a limited company, corporation tax is due on the profits of each accounting period. Your accounting period is usually 12 months and is set by your year-end date.

Payment deadline

Corporation tax must be paid no later than 9 months and 1 day after the end of your accounting period. So if your year end is 31 March 2025, the corporation tax for that period is due by 1 January 2026. If your year end is 31 December 2025, it is due by 1 October 2026. This is different from the filing deadline: you must pay on time even if your accounts are not yet finalised. Many companies estimate and pay before the deadline, then adjust when the return is filed.

Filing deadline

The corporation tax return (CT600) and the computation must be filed with HMRC within 12 months of the end of the accounting period. So for a 31 March 2025 year end, the return is due by 31 March 2026. Late filing can result in penalties. HMRC guidance on corporation tax deadlines sets out the full rules.

What you need to file and pay

You need to:

1. Prepare accounts for the period (for the company and for HMRC).
2. Calculate the corporation tax liability (profits, adjustments, reliefs).
3. File the CT600 and computation with HMRC.
4. Pay the tax by the 9-month-and-1-day deadline.

Your accountant can do steps 2–4; many also prepare the accounts. At Figures we handle Statutory Accounts & Tax so you meet both Companies House and HMRC deadlines.

How this fits with other UK tax deadlines

Companies House

Your annual accounts (the set that goes to Companies House) are due within 9 months of the year end. So for a 31 March 2025 year end, they are due by 31 December 2025. The same underlying figures feed your corporation tax return; the two filings are linked but have different deadlines.

VAT

If you are VAT registered, your VAT return and payment have their own cycle (usually quarterly or monthly). Those deadlines are separate from corporation tax.

Making Tax Digital (MTD) for income tax

From April 2026, many sole traders and landlords will need to follow MTD for income tax: keep digital records and submit quarterly updates to HMRC, plus an end-of-period statement and final declaration. This does not change when corporation tax is due for limited companies, but it is a major change for the self-employed. If you are a sole trader or landlord, you may need to sign up and use compatible software. GOV.UK MTD for income tax has the latest.

Planning so you do not miss deadlines

• Mark your year end and work backwards: accounts due when, tax return due when, tax payment due when.
• Get your records and supporting information to your accountant in good time so they can file before the 12-month deadline.
• If you think you will miss a deadline, contact HMRC and your accountant early. Time-to-pay arrangements or an extension may be possible in some cases.

UK tax and legal accuracy

The deadlines described apply to the current UK rules for corporation tax and Companies House. Tax years 2024/25 and 2025/26 may see further changes. This article is for informational purposes only and does not constitute professional tax or financial advice. Please speak to a qualified accountant before taking action.

Frequently asked questions

When is corporation tax due for a new company?

The same rule applies: 9 months and 1 day after the end of your first accounting period. Your first period starts when the company is incorporated and usually runs for 12 months to your chosen year end.

What if my accounting period is shorter than 12 months?

Short periods (e.g. when you change year end) still have a payment deadline 9 months and 1 day after the period end, and a filing deadline 12 months after the period end.

Do I pay corporation tax before or after the return is filed?

You must pay by the 9-month-and-1-day deadline even if the return is not yet filed. Many companies pay an estimated amount and then true up when the return is submitted.

What is Making Tax Digital and does it affect my limited company?

MTD for income tax (from April 2026) applies to sole traders and landlords above the threshold. MTD for corporation tax is not yet in place for most companies. So for now, corporation tax deadlines for limited companies are unchanged by MTD.

Can I get an extension for corporation tax?

HMRC can allow extra time to file in certain circumstances. Payment is still due by the normal deadline unless you have a time-to-pay arrangement. Your accountant can advise.

Summary and next steps

Corporation tax in the UK is due 9 months and 1 day after the end of your accounting period; the return is due within 12 months. Keep track of your year end and both deadlines, and get your information to your accountant early. If you are a sole trader or landlord, also watch for MTD for income tax from April 2026.

If you would like help with corporation tax, year-end accounts, or Making Tax Digital, we would be glad to help. At Figures we work with UK limited companies and sole traders to stay compliant. You can book a discovery call or look at our Statutory Accounts & Tax service.