When is Corporation Tax Due?
When is Corporation Tax Due?
For most UK limited companies, Corporation Tax is due 9 months and 1 day after the end of the Corporation Tax accounting period.
When is Corporation Tax due?
For most UK limited companies, Corporation Tax is due 9 months and 1 day after the end of the Corporation Tax accounting period.
Corporation Tax is normally payable 9 months and 1 day after your accounting period ends.
For example, if your accounting period ends on 31 March 2026, your Corporation Tax payment will normally be due on 1 January 2027.
Your Company Tax Return (CT600) has a different deadline: it is normally due 12 months after the end of the accounting period.
Guide reviewed for current UK Corporation Tax rules • September 2026
The three company deadlines that are often confused
Corporation Tax payment, the Company Tax Return and Companies House accounts have separate deadlines. Paying your Corporation Tax does not mean that your CT600 or company accounts have been filed.
Corporation Tax Due Date Calculator
Enter the final day of your Corporation Tax accounting period to estimate your normal Corporation Tax payment and CT600 filing dates.
This calculator covers the normal Corporation Tax deadline. Different payment rules can apply to large and very large companies, companies with associated companies, short accounting periods and some specialist businesses.
Corporation Tax deadline examples
The easiest way to understand the rule is to work forward from the final day of the Corporation Tax accounting period.
| Accounting period ends | Corporation Tax normally due | CT600 normally due |
|---|---|---|
| 31 January 2026 | 1 November 2026 | 31 January 2027 |
| 28 February 2026 | 1 December 2026 | 28 February 2027 |
| 31 March 2026 | 1 January 2027 | 31 March 2027 |
| 30 June 2026 | 1 April 2027 | 30 June 2027 |
| 30 September 2026 | 1 July 2027 | 30 September 2027 |
| 31 December 2026 | 1 October 2027 | 31 December 2027 |
What date is the Corporation Tax deadline based on?
The deadline is based on the end of your Corporation Tax accounting period, not simply the date on which you incorporated the company or the date on which you happen to prepare your accounts.
Established companies
For an established company, the Corporation Tax accounting period will often correspond with the company's financial year.
New companies
A first set of statutory accounts can cover more than 12 months, but a Corporation Tax accounting period cannot normally exceed 12 months. A new company can therefore have two Corporation Tax accounting periods within its first set of accounts.
Corporation Tax timeline for a typical limited company
Your accounting period ends
Your bookkeeping can then be finalised and the taxable profit calculated after tax adjustments, allowances and reliefs.
Prepare the statutory accounts and tax computation
Your accounting profit is not necessarily the same as your taxable profit. Adjustments may be required for expenses, capital allowances, losses, pensions and other tax items.
9 months and 1 day — pay Corporation Tax
For a company within the normal payment regime, Corporation Tax must usually have been paid by this point.
12 months — file the Company Tax Return
The Company's CT600, tax computation and supporting accounts must normally be submitted to HMRC by the filing deadline.
How do I know how much Corporation Tax is due?
Corporation Tax is calculated from the company's taxable profits, rather than simply applying a tax percentage to turnover or the profit shown in the statutory accounts.
Your accountant will normally consider items including:
- trading profits and other taxable income
- disallowable business expenses
- capital allowances on qualifying expenditure
- company pension contributions
- tax losses brought forward or carried back where available
- chargeable gains
- associated companies
- loans to directors or shareholders where relevant
- available Corporation Tax reliefs
This is why it is sensible to prepare your accounts and tax calculation well before the payment deadline, even though the CT600 itself can normally be submitted later.
See our guide to how to reduce Corporation Tax legally for tax-planning ideas that may be relevant before or around the company year end.
Do all companies have 9 months and 1 day to pay?
No. The normal rule does not apply to every company.
Companies with sufficiently high profits may have to make Corporation Tax payments by instalments rather than making one payment 9 months and 1 day after the accounting period.
Profits above £1.5 million
A company whose annual taxable profits exceed the relevant £1.5 million threshold will normally enter the quarterly instalment payment regime, subject to the detailed rules and exceptions.
For a normal 12-month accounting period, instalments are generally due at approximately months 7, 10, 13 and 16 from the beginning of the accounting period.
Profits above £20 million
Very large companies can have even earlier payment dates, with instalments falling during the accounting period itself.
Specialist calculations should be made well before the first instalment becomes due.
How do you pay Corporation Tax?
Corporation Tax is paid to HMRC using the 17-character Corporation Tax payment reference for the relevant accounting period.
This is important because your Corporation Tax payment reference normally changes for each accounting period. Do not automatically reuse a reference saved in online banking from an earlier year.
| Payment method | Typical HMRC processing | Points to remember |
|---|---|---|
| Online/mobile bank payment | Usually very fast | Use the correct 17-character reference. |
| Faster Payments | Usually same or next day | Check your bank's payment limits. |
| CHAPS | Normally same working day | Your bank may charge a fee. |
| Bacs | Usually 3 working days | Do not leave payment until the deadline. |
| Direct Debit | Allow longer for first setup | The first Direct Debit normally needs several working days. |
| Debit / corporate credit card | Payment accepted on payment date | Personal credit cards cannot be used. Fees can apply to corporate cards. |
Where can I find my Corporation Tax payment reference?
Your Corporation Tax payment reference is a 17-character reference relating to the specific accounting period you are paying.
You can normally find it:
- on HMRC's notice to deliver a Company Tax Return
- on Corporation Tax reminders from HMRC
- inside the company's HMRC online account
- from your accountant when your Corporation Tax calculation is prepared
What happens if Corporation Tax is paid late?
HMRC can charge late-payment interest on Corporation Tax that is not paid by the required date. The longer the liability remains unpaid, the more interest can accrue.
If you have missed the deadline, paying the tax as quickly as possible can therefore prevent further interest accumulating.
Tax unpaid?
Pay as soon as you can. If you cannot pay the liability in full, contact HMRC promptly rather than ignoring the debt.
CT600 also late?
Late filing is a separate matter and can result in penalties. File the outstanding return as soon as possible.
What if my company cannot afford its Corporation Tax bill?
Do not simply allow the deadline to pass without taking action. If the company is experiencing temporary cash-flow difficulties, HMRC may consider a Time to Pay arrangement.
HMRC may want to understand:
- why the company cannot pay on time
- how much it can afford to pay immediately
- its expected future income and expenditure
- how quickly the outstanding tax can realistically be cleared
- whether other taxes and filing obligations are up to date
Interest may continue to apply, so a payment arrangement should not be viewed as an interest-free extension of the Corporation Tax deadline.
When is Corporation Tax due for a new limited company?
A new company's first Corporation Tax deadline depends on when the company becomes active for Corporation Tax and the accounting periods that result.
This can be confusing because your first Companies House accounts can cover a period longer than 12 months, whereas a Corporation Tax accounting period normally cannot.
What if there is no Corporation Tax to pay?
A company may have no Corporation Tax liability because, for example, it made a loss or available reliefs reduced the liability to nil.
However, having no Corporation Tax to pay does not necessarily mean that there is no Company Tax Return filing obligation. If HMRC has issued a notice requiring a return, the return generally still needs to be filed.
A genuinely dormant company may be treated differently, depending on its circumstances and what HMRC has requested.
Do you have to wait until the CT600 deadline to file?
No. The 12-month date is the normal latest filing date, not a recommended filing date.
Preparing and filing earlier can give directors much better visibility of the Corporation Tax bill and reduces the risk of discovering a liability shortly before it must be paid.
Since April 2026, companies generally need appropriate commercial software to submit their Company Tax Return electronically to HMRC. An accountant can prepare the statutory accounts, Corporation Tax computation and CT600 and deal with the electronic submission.
Corporation Tax deadlines at a glance
| Question | Typical answer |
|---|---|
| When is Corporation Tax due? | 9 months and 1 day after the accounting period ends |
| When is the CT600 due? | 12 months after the accounting period ends |
| Is Corporation Tax due before the tax return? | Yes, normally around 3 months earlier |
| Can large companies have earlier deadlines? | Yes — quarterly instalment payments can apply |
| Does the payment reference change? | Yes — use the reference for the relevant accounting period |
| Can Corporation Tax be paid early? | Yes |
Frequently asked questions about Corporation Tax due dates
When is Corporation Tax due after the year end?
When is Corporation Tax due for a 31 March year end?
When is Corporation Tax due for a 31 December year end?
Is Corporation Tax due 9 months after the year end?
Is the CT600 due at the same time as Corporation Tax?
Can I pay Corporation Tax before it is due?
What happens if the company cannot pay Corporation Tax?
Do I still file a CT600 if there is no tax to pay?
Where do I find my Corporation Tax payment reference?
Need your company accounts and Corporation Tax return filed?
The Online Accountants provides fixed-price company accounts and Corporation Tax filing for UK limited companies. We calculate the Corporation Tax liability, prepare the CT600 and statutory accounts and make sure you know what needs paying and when.