How to Pay Corporation Tax: HMRC Deadlines, Payment Methods & Late Interest

Calculating your Corporation Tax liability is only the first step in managing your company’s fiscal responsibilities; ensuring that it is paid on time is equally, if not more, important. HMRC enforces extremely strict deadlines for corporate tax payments, and unlike the individual Self Assessment system, the payment deadline for small businesses actually falls **before** the statutory deadline to file your company tax return (CT600). Failing to pay your Corporation Tax by the exact deadline will invariably result in late payment interest charges and potential financial penalties that compound over time. It is absolutely crucial to make sure you claim all your allowable business expenses well in advance to minimise your final tax bill before the payment window closes. In this exhaustive, highly detailed guide, we review every aspect of how to pay your Corporation Tax, including the precise timelines, acceptable HMRC payment methods, step-by-step mathematical examples of how late payment interest is calculated in the 2026/27 tax year, and strategies to ensure your business remains perfectly compliant.

Understanding the Corporation Tax Payment Deadlines

The timeline for paying your Corporation Tax is strictly tied to your company’s accounting period. The rules are divided based on the size of your company’s taxable profits. It is imperative that directors understand which category their business falls into, as the deadlines vary significantly.

Standard Deadline for Small and Medium Companies

For the vast majority of UK limited companies—specifically those with taxable profits up to £1.5 million—the deadline to pay your Corporation Tax is exactly **9 months and 1 day** after the end of your accounting period. For example, if your company’s financial year ends on 31 December, your payment is due by **1 October** of the following calendar year. It is highly important to note that while your payment is due at this time, your actual company tax return (form CT600) is not legally due until 12 months after the end of your accounting period. This means you must calculate your tax and pay it three months before the final filing deadline.

Installment Deadlines for Large Companies

Companies with taxable profits exceeding £1.5 million are classified as “large” and are subject to an entirely different payment regime. These companies must pay their Corporation Tax in four quarterly installments. Two of these installments are due *during* the accounting period, and the remaining two are due after it ends. For a standard 12-month accounting period, the payments are due on the 14th day of the 7th, 10th, 13th, and 16th months following the start of the accounting period. If your profits exceed £20 million, you are classified as “very large” and must pay your installments even earlier (in the 3rd, 6th, 9th, and 12th months of the accounting period).

Accepted HMRC Payment Methods and Clearance Times

HMRC requires all Corporation Tax payments to be made electronically. You cannot pay at the Post Office, and cash payments are strictly forbidden. The time it takes for your payment to clear depends entirely on the method you choose. It is your responsibility to ensure the funds reach HMRC’s bank account on or before the deadline date, not just that they leave your account on that date. If the deadline falls on a weekend or a bank holiday, your payment must reach HMRC on the last working day *before* the deadline.

Same Day or Next Day Payment Methods

If you are approaching the deadline rapidly, you must use a fast payment method. The following options will typically clear on the same day or the next working day:

• Faster Payments: This is the most common method via online business banking. It usually clears within a few hours, even on weekends.
• CHAPS: A highly secure bank-to-bank transfer, guaranteed to arrive on the same day if submitted before your bank’s cut-off time. It usually incurs a fee from your bank.
• Online via Corporate Debit or Credit Card: You can pay directly on the HMRC portal. Be aware that corporate credit cards may incur a non-refundable surcharge. Personal credit cards cannot be used.

3 to 5 Working Days Payment Methods

If you have several days before the deadline, you can use slower, more automated methods:

• Direct Debit (Single Payment): You can set this up through your HMRC online account. It takes 5 working days to process the first time you set it up, and 3 working days for subsequent payments.
• BACS: A standard electronic transfer that takes 3 full working days to clear.

The Crucial 17-Character Payment Reference Number

Whenever you make a payment to HMRC, you must include your specific 17-character Corporation Tax payment reference number. This number is unique to your company and, critically, it is unique to the specific accounting period you are paying for. It is usually formatted as your 10-digit Unique Taxpayer Reference (UTR) followed by “A” and a sequence indicating the period (e.g., 1234567890A00101A). If you use an incorrect reference, or reuse last year’s reference, your payment will be misallocated. This will result in HMRC’s automated systems flagging your account as unpaid, triggering late payment interest and debt collection letters, even though the money has left your bank account.

Mathematical Breakdown: Calculating Late Payment Interest

If you fail to pay your Corporation Tax by the statutory deadline, HMRC will automatically charge **late payment interest**. This interest accrues daily from the due date until the date the payment clears in HMRC’s account. The interest rate is not fixed; it tracks the Bank of England base rate, plus a statutory penalty margin (typically 2.5%). Let’s walk through a detailed, step-by-step mathematical example of how this interest is calculated.

Scenario: Company XYZ Ltd has a Corporation Tax bill of £25,000 for the year ending 31 December 2025. The payment deadline is 1 October 2026. However, the company faces cash flow issues and does not make the payment until 15 November 2026. The HMRC late payment interest rate during this period is assumed to be 7.75% per annum.

1. Step 1: Calculate the Number of Days Late:
   The payment was due on 1 October. The payment cleared on 15 November. Let’s count the days: October has 31 days, so 1st to 31st is 31 days. Plus 15 days in November = 46 days late in total.
2. Step 2: Calculate the Daily Interest Rate:
   Annual interest rate = 7.75% (or 0.0775 in decimal).
   Daily rate = 0.0775 / 365 = 0.000212328.
3. Step 3: Calculate the Daily Interest Charge:
   Tax outstanding = £25,000.
   Daily charge = £25,000 * 0.000212328 = £5.3082.
4. Step 4: Calculate the Total Interest Due:
   Total interest = Daily charge * Number of days late.
   £5.3082 * 46 days = £244.18.

Therefore, Company XYZ Ltd must pay the original £25,000 plus an additional £244.18 in interest. This interest is fully payable and, crucially, late payment interest paid to HMRC is *not* an allowable expense for Corporation Tax purposes. To estimate the interest and collection fees due on any overdue HMRC tax liabilities rapidly, use our Late Payment Interest Calculator.

What to Do if You Cannot Afford to Pay

If you realize your company does not have the liquid capital to pay its Corporation Tax bill, you must act before the deadline. Waiting for the deadline to pass and hoping HMRC won’t notice will lead to aggressive debt collection. Instead, you should contact HMRC’s Business Payment Support Service (BPSS) immediately to request a **Time to Pay (TTP) arrangement**.

A Time to Pay arrangement allows you to spread the cost of your tax bill over several months (typically 3 to 12 months, depending on your circumstances) via direct debit. While HMRC will still charge late payment interest on the outstanding balance during the TTP period, they will hold off on any late payment penalties or debt enforcement action, such as winding-up petitions, provided you stick strictly to the agreed payment schedule.

HMRC Repayment Interest: Earning Credit for Early Payments

Conversely, HMRC actually rewards companies that pay their Corporation Tax early. If you pay your tax before the deadline, HMRC will pay you “credit interest” (also known as repayment interest). The rate for early payment interest is usually lower than the late payment penalty rate (typically base rate minus 1%, with a floor of 0.5%). This interest is calculated from the date you pay your tax until the normal due date. It is important to remember that any credit interest paid to your company by HMRC is considered taxable income and must be declared on your subsequent company tax return as interest received.

Summary of Best Practices for Corporation Tax Payment

To ensure total compliance and avoid unnecessary financial leakage through interest charges, company directors should adhere to the following best practices:

• Separate Tax Funds: Open a dedicated business savings account and transfer a percentage of your monthly revenue into it to build a tax reserve. Do not treat collected VAT or estimated Corporation Tax as operating cash flow.
• File Early: Although you have 12 months to file the CT600, aim to file it within 6 months of your year-end. This gives you absolute certainty over exactly how much tax you owe well before the 9-month payment deadline.
• Double-Check References: Always log into your HMRC online account to generate the correct 17-character payment reference for the specific accounting period you are paying. Never copy-paste last year’s reference.
• Account for Weekends: Always schedule your payments to clear at least 3 working days before the final deadline to act as a buffer against banking glitches or public holidays.

Frequently Asked Questions: Paying Corporation Tax

Q: What is the absolute final deadline to pay Corporation Tax in the UK for a small business?
A: For small and medium companies with profits up to £1.5 million, the absolute payment deadline is exactly 9 months and 1 day after the end of the accounting period. For instance, a company with a 31 March year-end must pay its tax by 1 January of the following year. Large companies must pay in quarterly installments.

Q: What happens if I use the wrong payment reference number when paying HMRC?
A: If you use an incorrect or old 17-character Corporation Tax payslip reference, HMRC’s automated systems will not allocate the payment to your current tax bill. The funds will sit in a suspense account. As far as HMRC is concerned, your bill remains unpaid, and they will begin charging late payment interest and issuing debt collection notices. You must call the Corporation Tax helpline to manually reallocate the payment.

Q: Does HMRC pay interest if I pay my Corporation Tax early, and is it taxable?
A: Yes, HMRC pays “credit interest” if you pay your Corporation Tax before the official deadline. This interest accrues from the day you pay until the deadline. However, this interest is indeed classified as taxable income and must be explicitly declared on your next company tax return (CT600) under the interest received section.

Q: Can I pay my Corporation Tax using a personal credit card?
A: No, HMRC no longer accepts payments from personal credit cards for tax bills. You can use a corporate/business credit card, but you must be aware that a non-refundable handling surcharge will be applied by HMRC to cover processing fees. The most cost-effective methods are Faster Payments or BACS from your business bank account.

Q: Will I get a penalty for paying Corporation Tax late?
A: Initially, you will only be charged daily late payment interest on the outstanding balance, not a flat penalty fee. Flat penalties are generally reserved for late filing of the CT600 return, not late payment. However, if the debt remains unpaid for an extended period, HMRC may initiate debt collection procedures, which can incur additional enforcement fees and ultimately lead to a winding-up petition against the company.

Q: How do I set up a Time to Pay arrangement if I cannot afford the bill?
A: You must contact HMRC’s Business Payment Support Service (BPSS) before your deadline passes. You will need to explain your financial situation, provide a cash flow forecast, and propose a realistic monthly repayment plan (usually over 3 to 12 months). If accepted, you will pay via Direct Debit. Note that late payment interest will still accrue on the unpaid balance during this time.

Q: Can I offset Corporation Tax owed against a VAT refund HMRC owes me?
A: Generally, no. HMRC systems are largely segregated. You cannot simply choose to underpay your Corporation Tax because you are awaiting a VAT refund. You are expected to pay the Corporation Tax on time and separately await the VAT refund. In rare, complex insolvency cases, HMRC might manually offset debts, but as a standard trading company, you must handle them as separate transactions.

Q: What if my accounting period is shorter than 12 months?
A: If your accounting period is shorter than 12 months, the deadline rule remains the same: 9 months and 1 day after the end of that specific short period. You will need to calculate the tax proportionately for that period and generate a specific payment reference for it.

Q: Is late payment interest tax-deductible for my company?
A: No. Any late payment interest charged by HMRC for overdue Corporation Tax is not an allowable business expense. You cannot deduct it from your trading profits to lower your subsequent tax bill. It is a straight hit to your company’s net reserves.

Q: How do I know if my payment has been received by HMRC?
A: You should log into your HMRC online business tax account. It typically takes 3 to 6 working days for an electronic payment to show up as cleared on your digital dashboard, depending on the payment method used. Do not panic if it doesn’t show immediately the next morning, provided you used the correct reference and a valid payment method.