What is an Employer's PAYE Reference Number (or ERN)?

The Employer's PAYE Reference Number is also referred to as the Employer Reference Number or ERN. This is important information to keep after hiring your first employee.

Employers registered with HMRC receive many reference numbers, which can be confusing, but important to keep track of them. When it comes to buying employer liability insurance, your employer's PAYE Reference Number (ERN) is especially important.

What is an employer reference number?

An Employer PAYE Reference Number is assigned to any company that registers with HMRC as an employer. It is a unique series of letters and numbers used by the tax inspector and others to identify your business.

This link consists of two parts: a three-digit HMRC office number and a reference number that is unique to your business. It usually looks something like this: 123/A45678 or 123/AB45678 (although there may be exceptions).

When do I need an ERN?

HMRC needs your ERN in a variety of circumstances. Perhaps most importantly, you will need it as you approach the end-of-year PAYE return. An invalid or missing ERN is one of the most common reasons for the rejection of year-end returns. You need to know this number to meet your statutory reporting obligations.

It is also likely that you will be asked for your ERN at some point. Employees often need their employer's PAYE reference number when applying for tax credits, student loans, and few other tasks. You may also need to put it on payslips.

It is important to have your ERN available when purchasing employer liability insurance. This is done so that you can identify the companies the employee has worked in if there's a claim a long time after the event.

What if I lost my ERN?

It is important that you keep your employer's PAYE reference number as you will need it regularly throughout the tax year. If you lose it, you can find it in PAYE letters or emails from HMRC. It is also displayed on any P45 or P60 for previous or current employees.

Exceptions to PAYE

In some cases, you do not need to register under PAYE and therefore do not have a PAYE employer reference number. You do not need to register with the PAYE system if:

  • your employees are self-employed or are paid through an agency ;
  • your employees earn less than £ 118 per week;
  • your employees are unpaid volunteers;
  • your business is based in the Channel Islands or the Isle of Man.

In case you require a consultation on the ERN topic - please contact Persona Finance (

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