Your Accounts Office reference number is the 13-character code HMRC assigns to every employer who registers for PAYE, and it exists to route your tax payments to the correct account. You’ll find it on the New Employer letter HMRC sent when you first registered, inside your HMRC online account, and stored in your payroll software. Enter it wrong on a payment, or confuse it with your separate Employer PAYE Reference, and the money can sit unallocated while HMRC’s systems treat you as if you haven’t paid.
What the Reference Looks Like
The code is exactly 13 characters and follows a fixed pattern: three digits, the letter “P,” another letter, and then either eight digits or seven digits ending in “X.”1HMRC Design Patterns. Accounts Office Reference A typical example is 123PX00123456. The opening three digits identify the HMRC tax office that handles your payroll. The remaining characters single out your business from every other employer in the system.
The Income Tax (Pay As You Earn) Regulations 2003 require employers to include this reference on returns and notifications submitted to HMRC, though the regulations don’t define the format — that’s an internal HMRC convention.2Legislation.gov.uk. The Income Tax (Pay As You Earn) Regulations 2003 In practice, the reference works as a routing code. Without it, HMRC cannot credit your income tax and National Insurance payments to the correct employer record, and unallocated funds can trigger penalty notices even though the money has left your bank account.
Where to Find Your Accounts Office Reference
HMRC issues a New Employer letter when you first register for PAYE, and that letter shows both your Employer PAYE Reference and your Accounts Office reference.3HM Revenue & Customs. Debt Management and Banking Manual – DMBM519335 Keep the letter in your permanent tax records. If your business still receives physical payment slips, the reference also appears on the front of the employer payment booklet (form P30BC).4HM Revenue & Customs. CIS300 – Construction Industry Scheme: A Guide for Contractors
For digital access, log in to your HMRC online account and open your employer tax summary. The reference is displayed there. Most commercial payroll packages store it too, usually under company settings or employer details, because the software needs it to authenticate Real Time Information submissions.
If every copy has been lost, call the HMRC employer helpline on 0300 200 3200, or +44 151 268 0558 from outside the UK.5GOV.UK. Employers: General Enquiries You’ll need to verify your identity through other means, since HMRC won’t quote the reference over the phone without confirming who’s asking. Webchat is available through the employer enquiries page on GOV.UK.
Accounts Office Reference vs Employer PAYE Reference
The two references trip up a lot of employers because both start with the same three-digit tax office number. They serve different purposes and can’t be used interchangeably.
Your Employer PAYE Reference follows a format like 123/AB45678: three digits, a forward slash, then a mix of letters and numbers. HMRC uses it to identify your PAYE scheme on submissions, forms, and correspondence. The Accounts Office reference (for example, 123PA00012345) identifies your payment account and must appear on every bank transfer or other payment you send to HMRC.6GOV.UK. Pay Employers’ PAYE – Reference Numbers for Early and Late Payments Enter your Employer PAYE Reference in the payment reference field by mistake and HMRC’s automated system won’t match the payment to your account.
When You Need a 17-Character Version
You don’t always need 17 characters. If you’re paying on time and in the correct tax month, the standard 13-character Accounts Office reference works on its own. You only add a four-digit suffix when you make an early or late payment, meaning one that falls outside the tax month it covers.6GOV.UK. Pay Employers’ PAYE – Reference Numbers for Early and Late Payments
The suffix has two parts: the last two digits of the tax year, followed by the two-digit tax month number. For the 2025–2026 tax year, the tax year digits are “26.” Tax months don’t follow the calendar. They run from the 6th of one month to the 5th of the next, starting with month 01 (6 April to 5 May) through month 12 (6 March to 5 April).6GOV.UK. Pay Employers’ PAYE – Reference Numbers for Early and Late Payments A payment covering September 2025 (tax month 06) would get the suffix “2606,” producing a full reference like 123PA000123452606.
If you pay quarterly, the suffix uses the tax month that ends the quarter rather than a single month. The four quarters and their suffix month numbers are:
- 6 April to 5 July: month 03
- 6 July to 5 October: month 06
- 6 October to 5 January: month 09
- 6 January to 5 April: month 12
Update the suffix every time you make an early or late payment. It isn’t a one-time setup. Getting the suffix wrong means HMRC allocates the money to the wrong period, and your account may show an unpaid balance for the month you were actually trying to cover.
Using the Reference on a Payment
For bank transfers, enter your full Accounts Office reference in the payment reference field: 13 characters for an on-time payment, 17 if the payment is early or late. Double-check before confirming, because a payment sent with the wrong reference generally requires a phone call to HMRC to reallocate and can take weeks to sort out.
After paying, your HMRC online account should update within six working days to show the payment.7GOV.UK. Pay Employers’ PAYE – Check Your Payment Has Been Received If it doesn’t appear after that window, contact HMRC before the next deadline passes.
If You’re a CIS Contractor
Contractors registered under the Construction Industry Scheme use the same Accounts Office reference for CIS deductions as for PAYE. When you register for CIS and already have employees, HMRC converts your existing PAYE scheme into a combined PAYE/CIS scheme rather than issuing a separate account.8GOV.UK. What You Must Do as a CIS Contractor – Pay Deductions to HMRC You make a single monthly or quarterly payment covering PAYE tax, National Insurance, and CIS deductions together, and the same reference formatting rules apply.