The Corporation Tax reference number you pay with is 17 characters long: your company's 10-digit UTR, then seven characters that name the accounting period. You do not work it out, you copy it from HMRC, because it changes every period.
The short answer
| Question | Answer |
|---|---|
| How long is it? | 17 characters |
| What does it look like? | 1234567890A00102A |
| What is inside? | The company UTR, then A001, a two-digit period number and a final letter |
| Where is it? | Notice to deliver a company tax return, HMRC reminders, HMRC online account |
| Does it stay the same? | No. It changes with each accounting period |
| Is it the UTR? | No. The UTR is only the first 10 digits |
Two numbers share the name "Corporation Tax reference". One identifies the company. The other sends a payment to one accounting period, and this page is about that one.
Identifies the company for Corporation Tax.
- Stays the same for the life of the company
- The number HMRC asks for when you call
- Paid with on its own, the money is held without a period
Pays Corporation Tax for one accounting period.
- Starts with the company UTR
- Copied from the notice, a reminder or the online account
- Not reusable: it changes with each accounting period
What the 17 characters mean
GOV.UK's payment guidance says only that the reference has 17 characters. The breakdown sits in HMRC's own Corporation Tax manual, which shows the "payslip reference" as 1234567890 A001 01 A.
| Block | Position | Example | What HMRC's manual calls it |
|---|---|---|---|
| 1 | Characters 1 to 10 | 1234567890 | The 10 digit unique reference, the UTR |
| 2 | Characters 11 to 14 | A001 | Head of Duty and case ID, "always A001 for CT" |
| 3 | Characters 15 and 16 | 02 | The accounting period number as shown on HMRC's system |
| 4 | Character 17 | A | The duty type |
Three details that guides usually get wrong:
- The spaces are not part of it. The 17 characters are counted without them.
- The last letter is not a check digit. The manual calls it the duty type:
Afor assessment,Pfor penalty. - The two digits are not a month. They are a period number on HMRC's record.
Read the reference, do not build it. The breakdown comes from HMRC's internal manual. GOV.UK gives the public no formula, only the places to copy the 17 characters from.
Why the reference changes every period
HMRC collects Corporation Tax, interest and late filing penalties one accounting period at a time. The reference has to say which period the money is for.
- Characters 1 to 14 stay the same for the life of the company.
- Characters 15 and 16 move with each accounting period.
- GOV.UK puts it plainly: the reference "changes with each accounting period, so you'll need to use a different one each time you pay".
GOV.UK also warns about the commonest cause of error. If you saved HMRC as a payee, "your bank automatically saves the reference number you last used".
Why you cannot count the two digits yourself
Many guides say 01 is your first year and 02 your second. HMRC's manual describes something less tidy.
HMRC's system numbers each accounting period "in order of the creation of the AP record". Creation order is not always calendar order.
| What happened to the company | Effect on the period number |
|---|---|
| First accounts cover more than 12 months | Two tax periods in that first stretch, so two numbers are used before year two |
| An accounting period was replaced on HMRC's record | The old period keeps its number, the replacement gets a new one |
| A dormant period sits on the record | It takes a number that is not displayed, and that number can be lost |
The manual draws the conclusion itself. The sequence "does not always agree with the date order" of the periods, and a record "sometimes has a missing AP number".
Counting years fails for a company that started dormant, had a long first period or changed its year end.
Where to find your Corporation Tax payment reference
GOV.UK names three places.
| Source | Where exactly | Good to know |
|---|---|---|
| Notice to deliver a company tax return | The letter HMRC issues for a period, form CT603 | Arrives by post, so check who receives the company's mail |
| HMRC reminders | Any reminder about that period | Covers that period only |
| HMRC online account | "view Corporation Tax statement", "accounting periods", then the period | The quickest route from abroad |
In the online account, the steps are:
- Sign in to the company's HMRC online account.
- Choose "view Corporation Tax statement".
- Choose "accounting periods".
- Select the period you are paying, and check its end date.
- Copy the 17 characters shown for that period.
Some GOV.UK pages word the path as "view account", then "accounting period". Expect either label.
If you cannot find the reference
Work down this list before you pay.
- No letter to hand. Use the online account instead.
- No online access. Ask whoever holds the company's mail for the latest notice or reminder.
- An agent files for you. Ask them for the reference for the exact period end date.
- Still nothing. Call HMRC's Corporation Tax line with the company's 10-digit UTR.
Four shortcuts to avoid:
- Reusing last year's reference.
- Paying with the 10-digit UTR alone.
- Adding
A00101Ato the UTR by guesswork. - Using the PAYE reference you pay with every month.
What happens when you pay with the wrong reference
GOV.UK's warning is short: the payment "may be delayed or used to pay a different tax bill that you owe". HMRC's manual shows where the money goes in each case.
| What you typed | Where the payment lands | What you see |
|---|---|---|
| Right UTR, an earlier period's digits | On that earlier period | That period looks overpaid, the current one unpaid |
| The 10-digit UTR alone | The company's suspense record | A payment on account, matched to no period |
| Right UTR, a period number that does not exist | The company's suspense record | The same |
| A UTR that HMRC cannot match | A holding account outside the company's record | Nothing in the online account |
| Another tax's reference, such as the PAYE one | Possibly against a different tax bill | Corporation Tax still showing as due |
The practical effects are the same in every row:
- The money is with HMRC, but the period you meant to pay still shows a balance.
- HMRC "may charge you interest if you do not pay on time".
- HMRC can keep sending payment requests until the payment is matched.
- An apparent overpayment on another period can be moved or repaid automatically.
How to get a misallocated payment moved
GOV.UK's route is one line: contact Corporation Tax general enquiries and "ask for your payment to be moved". In practice:
- Wait 3 working days after an electronic payment before contacting HMRC.
- Check that the payment has left your bank account. If it has not, speak to your bank first.
- Check the online account. GOV.UK says it "should be updated within a few days".
- Contact HMRC, say the payment went in under the wrong reference, and ask for it to be moved.
- Give the accounting period it was meant for, by its end date.
| Channel | Detail |
|---|---|
| Phone, from the UK | 0300 200 3410 |
| Phone, from outside the UK | +44 151 268 0571 |
| Opening hours | Monday to Friday, 8am to 6pm, closed on bank holidays |
| Post | Corporation Tax Services, HM Revenue and Customs, BX9 1AX, United Kingdom |
| HMRC asks for | The company's 10-digit UTR |
The UTR is the only item HMRC lists. It is still worth having these ready:
- the amount and date of the payment
- your bank's transaction reference
- the reference you typed, and the one you meant
Paying from a bank account outside the UK
The reference rule does not change when the money comes from abroad. A few points do.
- GOV.UK publishes an IBAN and BIC for two accounts: HMRC Cumbernauld and HMRC Shipley.
- Your notice or reminder says which one to use. If unsure, GOV.UK says HMRC Cumbernauld.
- Pay in sterling. Your bank may charge you for any other currency.
- Put the 17 characters in the payment reference field, without spaces.
- GOV.UK gives clearing times for UK transfers only, so leave a margin on an international one.
The reference is one small part of the annual routine. If you are still deciding whether to incorporate, see what running a UK company involves for a non-resident founder.
The numbers a director mixes up
A UK company can carry six references. Three identify something and three are used to pay.
| Number | Format | Issued by | What it is for |
|---|---|---|---|
| Company UTR | 10 digits | HMRC | Identifying the company for Corporation Tax |
| Corporation Tax payment reference | 17 characters, 1234567890A00102A | HMRC | Paying Corporation Tax for one accounting period |
| Employer PAYE reference | 123/AB456 | HMRC | Identifying a PAYE scheme |
| Accounts Office reference | 13 characters | HMRC | Paying PAYE |
| VAT number | GB plus 9 digits | HMRC | Identifying a VAT registration. The 9 digits are also the VAT payment reference |
| Company number | 8 characters | Companies House | Identifying the legal entity |
The pattern to remember:
- Corporation Tax is the only one whose payment reference changes every period.
- PAYE has one number to identify and another to pay.
- The company number never pays any tax.
The summary
| You want to | Answer |
|---|---|
| Read it | UTR, A001, two-digit period number, one letter |
| Find it | Notice to deliver, HMRC reminder, HMRC online account |
| Reuse last year's | No. It changes with each accounting period |
| Pay with the UTR alone | No. The payment is held without a period |
| Work out the two digits | No. Copy them from HMRC |
| Fix a wrong reference | Ask Corporation Tax general enquiries to move the payment |
Frequently asked questions
What is a Corporation Tax reference number?
The term covers two things. The company UTR is 10 digits and identifies the company. The payment reference is 17 characters and identifies the period you are paying.
How do I find my Corporation Tax reference number?
Look on the notice to deliver a company tax return, on any HMRC reminder, or in the company's HMRC online account under "view Corporation Tax statement".
How many characters is the Corporation Tax payment reference?
It is 17 characters: the 10-digit company UTR, then A001, a two-digit period number and one letter.
Is the Corporation Tax payment reference the same as the UTR?
No. The UTR is its first 10 digits and never changes. The payment reference adds seven characters that change with each accounting period.
Does the Corporation Tax payment reference change every year?
Yes. GOV.UK says it changes with each accounting period, so you need a different one each time you pay.
Can I work out the reference myself from the UTR?
You should not. HMRC numbers periods in the order its records were created, which does not always match the order of your financial years.
What happens if I pay Corporation Tax with only the UTR?
HMRC's manual says a payment with no accounting period is held on the company's suspense record. The period still shows as unpaid until HMRC moves it.
What happens if I use last year's reference?
The payment is credited to last year's period. That period looks overpaid, and the period you meant to pay still shows a balance.
How do I get HMRC to move a payment made with the wrong reference?
Call Corporation Tax general enquiries on 0300 200 3410, or +44 151 268 0571 from outside the UK. Have the company UTR ready and ask for the payment to be moved.
Which reference do I use to pay a late filing penalty?
GOV.UK says to use the 17-character payment reference for the accounting period the penalty applies to.
Sources
- GOV.UK: Pay your Corporation Tax bill
- GOV.UK: Pay your Corporation Tax bill, online or telephone bank transfer
- HMRC COTAX manual COM100: glossary, payslip reference
- HMRC COTAX manual COM1010: accounting period records and AP numbers
- HMRC COTAX manual COM90020: the payment record
- HMRC COTAX manual COM90060: suspense and payments in advance
- GOV.UK: Corporation Tax general enquiries
The 17-character length, the places to find the reference, the rule that it changes with each accounting period and the route for moving a payment are quoted from GOV.UK, consulted in October 2026. The block by block breakdown, the numbering of accounting periods and the description of where a mismatched payment is held come from HMRC's internal COTAX manual, which is written for HMRC staff and describes HMRC's systems rather than taxpayer obligations. Phone numbers and opening hours are those published on GOV.UK at the same date and can change. This is informational, not tax advice.