When Are Corporate Taxes Due? UK Corporation Tax Deadlines

Corporation Tax is usually due 9 months and 1 day after the end of your company's accounting period.

If you run a limited company, missing a Corporation Tax deadline costs you money before you even get the letter. That's because HMRC charges interest from the day after your payment is due. 

This guide explains when corporate taxes are due, how the penalty system works, and how to pay HMRC.

Key points

• Late payment and late filing have different consequences ⚠️
  Paying late results in daily interest charges on the outstanding tax bill, while filing late can trigger fixed penalties that increase the longer your return remains overdue. HMRC treats payment and filing as separate obligations.
• New companies and large companies face additional rules 🏢
  New companies can have multiple accounting periods in their first year, which come with extra filing requirements. Companies with profits above £1.5 million may need to make quarterly instalment payments instead of paying in a single lump sum.
• Dormant companies still have responsibilities 📝
  Dormant companies usually don't need to pay Corporation Tax or file a CT600, but they have to notify HMRC of their status and continue filing annual dormant accounts with Companies House.
• Staying organised helps you avoid missed deadlines 🚀
  Keeping accurate records throughout the year reduces the risk of missing your Corporation Tax deadlines. ANNA helps by automating bookkeeping, tracking important dates, and filing CT600 returns directly with HMRC.

How Corporation Tax deadlines work

Corporation Tax doesn't follow the standard UK tax year (6 April to 5 April). It follows your company's accounting period, which is typically 12 months and aligns with your company's year end.

Most companies have a 31 March or 31 December year end, but yours could fall on any date. That date determines everything: when your tax is due, when your return has to be filed, and when HMRC expects to hear from you.

When are corporate taxes due?

There are two key deadlines to keep track of:

• Payment deadline: 9 months and 1 day after the end of your accounting period
• Filing deadline: 12 months after the end of your accounting period

What counts as an accounting period?

Your company's accounting period for Corporation Tax purposes is usually the same as your financial year, but there are situations where they differ.

When you set up a limited company, your first accounting period starts on the date of incorporation. If that period lasts longer than 12 months (which can happen if you choose a year end that's more than 12 months after incorporation), HMRC splits it into two separate accounting periods, each with its own deadlines. 

Your accounting period can also end early if your company stops being liable for Corporation Tax, for example, if it becomes dormant or is wound up.

🧠 Good to know 

HMRC will tell you when they expect your return, but they base this on the information you provided when you registered. If your accounting period end has changed, make sure Companies House and HMRC both have the correct date.

What happens if you miss the payment deadline?

HMRC charges interest on late Corporation Tax from the day after the payment deadline. As of June 2026, the late payment interest rate is 7.75% per year, calculated daily on the outstanding balance.

For example, if your company owes £10,000 in Corporation Tax and pays one month late, you'd owe around £65 in interest on top of the original tax bill. The longer the debt remains unpaid, the more interest accrues.

There are no automatic financial penalties for paying late (unlike for filing late), but the interest charge is unavoidable and non-deductible, meaning you can't offset it against your Corporation Tax bill.

If you're struggling to pay on time, you may be eligible for a Time to Pay arrangement in some circumstances. You'll need to contact HMRC before the deadline, not after, and explain your situation. 

However, approval isn’t guaranteed. HMRC will assess whether you have a short-term cash flow problem rather than an inability to pay.

What happens if you miss the filing deadline?

Late filing penalties for the CT600 form are separate from the interest charged on late payment. The penalty structure for 2026/27 is:

If your company files its Corporation Tax return late for three consecutive accounting periods, the flat-rate penalties increase significantly. Instead of £200 for each late-filing penalty, you'll be charged £1,000. 

🧠 Good to know

HMRC can also raise an estimated tax assessment if you don't file. You'll then need to file your actual return to replace it. Until you do, the estimated bill stands, and you're liable for the full amount, even if it's more than you owe.

Large company quarterly instalment payments

If your company's annual profits exceed £1.5 million, you move onto a quarterly instalment payment (QIP) system. Rather than paying in one lump sum after the accounting period ends, you pay in four instalments during the accounting period.

For a 12-month accounting period, the instalments fall in months 7, 10, 13, and 16 (counting from the start of the period). Each instalment is based on your estimated tax bill for the year. If your estimate is too high or too low, the difference is adjusted once your final tax liability is confirmed .

The QIP threshold is reduced proportionally for associated companies. If your company is part of a group or has associated companies, the £1.5 million limit is split among them, which can unexpectedly pull smaller companies into the QIP regime.

For very large companies (profits above £20 million), an accelerated payment schedule applies, with instalments starting even earlier in the accounting period.

💡 Did you know? 

ANNA lets you file your Company Tax Return directly with HMRC from inside the app. You can prepare and submit your CT600 without a separate accountant for most straightforward returns, and track what you owe so there are no surprises at the payment deadline.

Dormant companies and Corporation Tax

A dormant company has no Corporation Tax bill and doesn't need to file a CT600, provided it has had no 'significant accounting transactions' during the period. HMRC has to be notified that the company is dormant, and Companies House requires a dormant account to be filed annually regardless.

If your company becomes active again, you need to tell HMRC within three months of resuming trading. The Corporation Tax deadlines then apply from the start of the new accounting period.

How to pay Corporation Tax

HMRC doesn’t accept personal cheques and, in most cases, won’t accept payment at a bank branch. 

The main Corporation Tax payment methods are:

• Online or telephone banking using HMRC's bank details and your 17-digit Corporation Tax reference number
• CHAPS for same-day payment (useful if you're close to a deadline)
• Direct Debit, which has to be set up in advance via your business tax account
• Debit card via the HMRC website

Your 17-digit payment reference is your 10-digit Unique Taxpayer Reference followed by the letter 'A' and the accounting period end date in the format DDMMYYYY. HMRC uses this to match your payment to the correct period.

Never miss a Corporation Tax deadline with ANNA

Keeping track of Corporation Tax deadlines is much easier when your bookkeeping, tax records, and filing tools are all in one place. 

If you run a limited company, ANNA helps you stay organised throughout the year, so there are no last-minute surprises when Corporation Tax deadlines arrive. 

Here’s what ANNA offers:

• Automatic bookkeeping: Stay on top of your business income and expenses year-round, and eliminate the need for manual spreadsheets
• Real-time tax estimates: See how much Corporation Tax you may owe as your profits grow
• Company Tax Return filing: Prepare and submit your CT600 directly to HMRC from within the app
• A dedicated business account: Access statements, transaction histories, and business documents whenever you need them
• Accountant-friendly tools: Share accurate financial data with your accountant and reduce time spent gathering paperwork
• Free director Self Assessment filing: Submit your Self Assessment tax return at no extra cost if you're a director with straightforward salary and dividend income
• Smart money pots: Set money aside for future tax bills, so you're prepared when it’s time to pay
• 24/7 support: Get help whenever you need it through in-app chat, whether you have questions about bookkeeping, tax deadlines, or filing your returns

Try ANNA today and stay on top of your Corporation Tax with ease.