Every business that registers with HMRC as an employer is issued an employer PAYE reference, and it follows a fixed pattern: three numbers, a forward slash, then between one and ten characters made up of letters and numbers, shown by HMRC as the example 123/AB456 [1]. It sits alongside a second, separate identifier, the 13-character Accounts Office reference in the format 123PA00012345, and the two are constantly confused [2].
That confusion has real consequences. Quote the wrong reference on a payment and it can be misallocated. Enter the wrong one on a pension declaration and the submission fails. Miss it entirely on a year-end return and the filing bounces. The employer PAYE reference is one of the most-used pieces of information in UK payroll, yet many employers are unsure what it is, where it lives, and how it differs from the other numbers HMRC hands out.
This guide sets out exactly what the employer PAYE reference is, the precise format it takes, every document it appears on, and how it differs from the Accounts Office reference and the company Unique Taxpayer Reference. It is written for the new employer setting up a scheme, the administrator filling in an HMRC form, and the accountant who has to explain the difference to a client for the tenth time.
Key takeaways
- The employer PAYE reference format is three digits, a forward slash, then one to ten letters and numbers, for example 123/AB456 [1].
- It is issued when a business registers as an employer and arrives by letter before the first payday [3].
- The Accounts Office reference is a different 13-character number used when paying HMRC, in the format 123PA00012345, with no forward slash [2].
- The company Unique Taxpayer Reference is a 10-digit number for Corporation Tax or Self Assessment, unrelated to payroll [4].
- The PAYE reference appears on the P45, P60, P11D and payslips, and is needed for the auto-enrolment declaration of compliance [5].
What the employer PAYE reference is
The employer PAYE reference is a unique reference number issued by HMRC to an employer when it sets up a PAYE scheme [5]. It identifies the scheme itself, not the business's tax affairs generally, which is why it is used on everything that flows between an employer and HMRC about payroll.
It goes by several names. HMRC's own service design guidance notes it may be called the employer PAYE reference, the Employer Reference Number (ERN), or simply the PAYE reference [1]. Payroll professionals and software often use "ERN" as shorthand. They all mean the same identifier.
Its purpose is to let HMRC trace and match an employer's records. Internally, HMRC uses the reference to identify the correct employer scheme when payroll data arrives, matching submissions to the right account [6]. For the employer, it is the number that proves which PAYE scheme a payslip, a return or a query belongs to.
The exact format
Getting the format right matters because HMRC forms validate against it. The reference is built from two parts separated by a forward slash.
| Part | What it is | Example |
|---|---|---|
| Office number | Three digits identifying the HMRC tax office catchment area | 123 |
| Employer reference | One to ten characters, letters and numbers, unique to the employer | AB456 |
HMRC's design pattern states the reference should be formatted as three numbers, a forward slash, then between one and ten characters that can be letters and numbers, and that the example shown to users should always be 123/AB456 [1]. The first three characters represent the tax office catchment area and the remaining characters represent the unique employer [5]. Because the second part varies in length, the reference does not have one fixed total length, which is a frequent source of "this doesn't look right" doubts that are in fact perfectly valid references.
When and how it is issued
The reference is not something a business chooses or applies for separately. It is generated when the business registers as an employer with HMRC, which is normally required when it starts employing staff or uses subcontractors for construction work, and is required even for a single-director company drawing a salary [3].
Timing is specific. An employer must register before the first payday in order to receive its employer PAYE reference number, which is sent in a letter, and it cannot register more than two months before it starts paying people [3]. That letter is the original source of the reference, so it is worth storing carefully from day one. Getting the scheme set up correctly at the start is the foundation for running compliant payroll, and Moonworkers' HMRC-recognised payroll software for SMEs uses the same PAYE reference on every submission it sends.
Where to find the employer PAYE reference
Because the reference is used so widely, it is printed on most of the documents an employer already holds. If the original registration letter has been lost, the number can be recovered from several places.
| Document or source | Whether it shows the PAYE reference |
|---|---|
| HMRC registration letter | Yes, the original source [[3]](https://www.gov.uk/register-employer) |
| Employee P60 | Yes [[5]](https://en.wikipedia.org/wiki/Employer_Reference_Number) |
| Employee P45 | Yes [[5]](https://en.wikipedia.org/wiki/Employer_Reference_Number) |
| P11D benefits return | Yes [[5]](https://en.wikipedia.org/wiki/Employer_Reference_Number) |
| Payslips | Often, depending on the layout [[5]](https://en.wikipedia.org/wiki/Employer_Reference_Number) |
| HMRC PAYE Online account | Yes [[7]](https://www.gov.uk/paye-online) |
| Letters from HMRC about PAYE | Yes [[1]](https://design.tax.service.gov.uk/hmrc-design-patterns/employer-paye-reference/) |
The most reliable long-term source is the PAYE Online account, because it does not rely on keeping a piece of paper. An employer that has activated its online access can view the reference there at any time [7]. For a business that issues only occasional payslips rather than running a continuous scheme, the reference still needs to appear correctly on each document, which is one reason an instant payslip generator records the scheme reference on every payslip it produces.
Employees, too, rely on the reference appearing on their documents. They may be asked for the employer PAYE reference when claiming tax credits, applying for student finance, or verifying employment, so accurate reproduction on the P60 and P45 is not just an employer convenience.
The Accounts Office reference: a separate number
The single most common mix-up is between the employer PAYE reference and the Accounts Office reference. They are issued at the same time and often appear on the same registration letter, but they do different jobs.
The employer PAYE reference identifies the PAYE scheme and is used on forms, returns and submissions. The Accounts Office reference identifies the payment account and is used when sending money to HMRC. An employer needs both to operate PAYE correctly.
The Accounts Office reference format
The Accounts Office reference is 13 characters long, in a format such as 123PA00012345: three digits, the letters PA, then eight further digits [2]. Crucially, unlike the PAYE reference, there is no forward slash after the three-digit office number [8].
This reference is quoted when paying PAYE, Class 1 National Insurance, and Construction Industry Scheme or student loan deductions [8]. It can be found in the HMRC online account, on the registration letter, and on most demands HMRC issues [8]. For a bank transfer, four extra characters are added to the 13-character reference when making an early or late payment, which tells HMRC which period the payment covers [8].
Why the distinction matters at payment time
Quoting the PAYE reference where HMRC expects the Accounts Office reference is a routine cause of misallocated payments. The payment reaches HMRC but is not matched to the scheme, and the employer then receives a demand for tax it has in fact already paid. Keeping the two references clearly labelled, the slash-format one for filing and the PA-format one for paying, removes this problem entirely. The mechanics of employer National Insurance payments, which use the same Accounts Office reference, are covered in Moonworkers' guide to employer National Insurance.
How the PAYE reference differs from the company UTR
A third number completes the set, and it belongs to a different part of the tax system entirely. The Unique Taxpayer Reference (UTR) is a 10-digit number used for Self Assessment or Corporation Tax [4]. A company uses its UTR when submitting a Company Tax Return, whereas the employer PAYE reference is used for payroll matters such as the end-of-year PAYE return and accessing tax codes and notices about employees.
A business commonly holds all three at once: a UTR for its Corporation Tax, an employer PAYE reference for its payroll scheme, and an Accounts Office reference for its PAYE payments. The table below sets them side by side.
| Reference | Format | Used for |
|---|---|---|
| Employer PAYE reference | 123/AB456 (slash) [[1]](https://design.tax.service.gov.uk/hmrc-design-patterns/employer-paye-reference/) | Payroll forms, RTI submissions, year-end returns [[4]](https://design.tax.service.gov.uk/hmrc-design-patterns/unique-taxpayer-reference/) |
| Accounts Office reference | 123PA00012345 (no slash) [[2]](https://design.tax.service.gov.uk/hmrc-design-patterns/accounts-office-reference/) | Paying PAYE, NIC, CIS and student loans to HMRC [[8]](https://www.tax.service.gov.uk/information/help?affinitygroup=&helpcategory=security&helpid=AccountsOfficereference&lang=eng) |
| Company UTR | 1234567890 (10 digits) [[4]](https://design.tax.service.gov.uk/hmrc-design-patterns/unique-taxpayer-reference/) | Corporation Tax and Company Tax Return [[4]](https://design.tax.service.gov.uk/hmrc-design-patterns/unique-taxpayer-reference/) |
Reading the format is the quickest way to identify which is which: a slash means PAYE, the letters PA mean payments, and a plain 10-digit run means Corporation Tax.
When an employer needs the PAYE reference
Beyond routine payroll filing, the reference is demanded in several situations that catch employers out because they arise less often.
Real Time Information and year-end returns
The reference identifies the scheme on every Real Time Information submission, so it underpins the Full Payment Submission and the Employer Payment Summary that recognised software sends each pay period. It is also needed to complete the end-of-year PAYE return and to access tax codes and notices about employees [4]. Because these submissions run through HMRC-recognised software rather than being typed in by hand, the reference is configured once in the payroll system and used automatically thereafter. Platforms embedding payroll into their own products handle this through an HMRC-recognised payroll API, where the scheme reference is part of the employer configuration.
The auto-enrolment declaration of compliance
Workplace pension duties bring the reference into play in a way many small employers do not expect. To submit the declaration of compliance to The Pensions Regulator, an employer needs its PAYE reference along with either its letter code or its Accounts Office reference number [9]. Where an employer runs more than one PAYE scheme, it must provide details for each of them separately [9].
The declaration is a legal duty with a hard deadline: it must be completed within five months of the duties start date, which is the date the employer took on its first member of staff, or the employer risks a fine [9]. The Pensions Regulator confirms the PAYE reference can be found on the letter it sends about automatic enrolment, on the HMRC registration letter, or from payroll software [10]. Employers can work through the wider process in Moonworkers' guide to the declaration of compliance.
Employers' liability insurance and other checks
The reference also surfaces outside HMRC's own systems. Employers' liability insurance records are tracked against the Employer Reference Number, which is why the number needs to be quoted accurately on insurance documentation as well as on payroll paperwork [5]. This is one reason the reference is treated as mandatory information on the P45 and P60 that employees carry between jobs.
Multiple PAYE schemes and grouped employers
Larger or more complex businesses can hold more than one PAYE reference. A group might run separate schemes for different divisions, or an employer might operate a second scheme for a distinct category of worker. Each scheme has its own employer PAYE reference and its own Accounts Office reference, and they must be kept separate in payroll records, in payments, and in any pension declaration [9].
For accountants and payroll bureaux, managing many references across many client schemes is a defining operational challenge. Each client employer brings its own PAYE reference and Accounts Office reference, and mixing them across clients causes exactly the misallocation problems described earlier. A multi-client payroll dashboard keeps each scheme's references bound to the right employer, so a bureau filing for dozens of clients does not have to track them by hand. For businesses running their own single scheme, the discipline is simpler but no less important: record both references once, label them clearly, and reproduce them exactly. Guidance on fixing the mistakes that follow a mis-keyed reference is set out in Moonworkers' guide to correcting payroll errors.
Conclusion
The employer PAYE reference is a small piece of data with an outsized role. It identifies the PAYE scheme on every payroll submission, appears on the documents employees carry between jobs, and is required for the pension declaration that every employer must file. Its 123/AB456 format is distinctive enough to tell it apart from the PA-format Accounts Office reference used for payments and the 10-digit UTR used for Corporation Tax, and reading the format is the fastest way to avoid quoting the wrong one.
As payroll continues to move towards submissions made automatically from inside recognised software and embedded engines, the reference itself fades into the background of daily work: configured once, applied to every filing without a second thought. The employers who stay clear of reference-related problems are simply those who record all three numbers accurately at the start and never let the slash-format and the PA-format numbers change places.
Frequently asked questions
What does an employer PAYE reference look like?
It is made up of three digits, a forward slash, and then between one and ten characters that can be letters and numbers, which HMRC illustrates with the example 123/AB456 [1]. The first three digits identify the tax office catchment area and the rest identify the individual employer [5]. Because the second part varies in length, two valid references can look quite different in total length.
Where can an employer find its PAYE reference if the letter is lost?
The reference appears on the P60, the P45, the P11D and usually on payslips, so any of those documents will carry it [5]. The most dependable source is the HMRC PAYE Online account, which shows the reference at any time once online access has been activated [7]. It also appears on letters HMRC sends about PAYE [1].
Is the employer PAYE reference the same as the Accounts Office reference?
No. They are two separate numbers issued at the same time. The employer PAYE reference identifies the scheme and is used on forms and submissions, in the format 123/AB456 [1]. The Accounts Office reference identifies the payment account and is used when paying HMRC, in the 13-character format 123PA00012345 with no forward slash [2]. Both are needed to run PAYE correctly.
Is the employer PAYE reference the same as a company UTR?
No. The Unique Taxpayer Reference is a 10-digit number used for Corporation Tax or Self Assessment, while the employer PAYE reference is used for payroll [4]. A company can hold both at once because they serve different tax purposes, one for its Company Tax Return and one for its payroll scheme.
Image prompt (Imagen): Wide landscape photograph of a UK payslip and an official HMRC letter lying on a wooden desk beside a calculator and a pen, warm natural light from the side, close realistic detail, shallow depth of field, documentary style, no readable text, no logos, no brand names.
