What is an employer reference number?

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An employer reference number is a unique combination of letters and numbers, also called an employer PAYE reference, PAYE reference number or just abbreviated to ERN. It is given to a business when it registers with HMRC as an employer, serving to identify the employer for employee income tax and national insurance purposes.

When it first employs someone, the business must register– typically online- as an employer with HMRC, who will issue a welcome pack that includes the employer reference number.

The employer reference number is in two parts. The first part is 3 digits, which identifies the HMRC office number that deals with the company’s PAYE (e.g. 135). The second part of the reference, which follows a forward slash, is the tax office’s reference for the employer itself. (e.g. AB56789).

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A business registered as an employer before 2001 will have an employer reference number in the form 135/A56789. Those registered after that date will take the form 135/AB56789.

The letter or letters in the employer’s reference number should be entered in upper case.

Don't confuse your employer reference number!

A business, particularly a limited company, is identified by a number of different references. The employer reference number issued by HMRC is entirely different to each of the following:

  1. Company registration number – issued by Companies House when a company is formed. It consists of 8 characters, typically 8 numbers or a combination of 2 letters followed by 6 digits (e.g. 07650432) and is used to identify a company by Companies House
  2. Unique taxpayer reference (UTR) – issued by HMRC, consisting of 10 digits (e.g. 9012345678); it’s used to identify a company for most tax-related purposes
  3. VAT number– issued by HMRC for companies which register for Value Added Tax. It consists of 9 numbers, with “GB” sometimes added as a prefix (e.g. GB123456789)

While these are all references the company will need to quote from time to time, it’s mainly the employer reference number that’s needed when dealing with PAYE matters.

Which employers do not need an employer reference number?

There are only a few exceptions, where businesses don’t need an employer reference number:

  • Businesses without any employees
  • Businesses where all employees are paid below the PAYE tax threshold (currently £10,600 a year) and certain other conditions are met
  • Businesses registered outside England, Wales, Scotland or Northern Ireland (for example, those formed in Jersey or Guernsey)

If you’re at all unsure whether these exceptions apply to your company, you should consult your accountant or HMRC directly.

When do I need the employer’s reference number?

Your ERN will be required in a number of different circumstances:

  1. When you complete your PAYE return at the end of each tax year. If the ERN is incorrect or missing, HMRC will reject the submission.
  2. When contacting HMRC about income tax and national insurance.
  3. Employees will sometimes ask for the ERN – for example, when they’re applying for tax credits, student loans or just completing their own tax affairs.
  4. It should be quoted on most payslips, P60s, P11Ds and P45s
  5. From 1 April 2012, it must be provided to the insurer when purchasing or renewing employers’ liability insurance. It will form part of a database to help establish, when a claim is made by an employee – perhaps some considerable time in the future – that the business had appropriate insurance when the claimant was employed by it. That means that the insurer would pick up any compensation bill, not the business itself.

Where can I find my employer reference number?

You can find your employer’s reference number from several sources:

  • In the Yellow Booklet supplied by HMRC when you first registered as an employer
  • On any historic payslip, P45, P60 or P11D issued to past or present employees
  • Other correspondence from HMRC about PAYE
  • If your outsource your payroll, your accountant or bookkeeper
  • As a last resort, you can call HMRC’s Employer Helpline on 0300 200 3200. While they can resend the reference to the employer, it may take up to two weeks to arrive.

If you don’t have any record of employer reference number, it may be because you are not registered as an employer. That’s no problem if the business doesn’t employ anyone, but if it does it’s imperative that you register immediately with HMRC.


All companies are required to maintain up to date company records. Inform Direct is the perfect free tool to help you easily keep everything up to date.


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