What is an employer PAYE reference (ERN) in the UK, and where can you find it?

If you’re hiring your first employee, you’ll soon be asked for an ERN. It’s one of those HMRC numbers you only notice when a form won’t let you continue without it.

This guide explains what an employer reference number (ERN) is, what it looks like, where you can find it, and what to do if it goes missing, with a 2025/26 tax-year lens and practical steps to help a growing business stay organised over time.

Why do you need an ERN?

HMRC uses your ERN to match PAYE submissions to the right employer. In day-to-day terms, it’s the reference you’ll use when you:

• set up payroll and send PAYE information to HMRC

• complete PAYE-related forms

• answer employee requests that ask for an employer PAYE reference

• share employer details with providers (for example, employer’s liability insurance)

This reference also helps keep your records tidy across the tax year, especially for companies that are scaling quickly and trying to keep employment admin consistent as headcount grows.

What is an employer reference number (ERN)?

An ERN is a unique HMRC reference for your PAYE scheme. Once you register as an employer, HMRC sends it to you (typically in an employer welcome pack / letter).

If you run more than one PAYE scheme (for example, different payrolls within the same group of companies), you may have more than one ERN. That’s why it’s useful to include the business name next to each reference in your payroll/admin tab (and to note which PAYE scheme it relates to), so you don’t waste time picking the wrong one.

What does an ERN look like?

Most ERNs have two parts:

• a 3-digit HMRC office number

• a second part made of letters and numbers

• a forward slash between them

Where can you find your ERN?

You’ll typically find your employer PAYE reference in:

• HMRC’s letter after you register as an employer (the most common place)

• PAYE paperwork and payroll documents, depending on what you generate, such as:

• P45s

• P60s

• P11Ds (if relevant)

• payroll reports (some payroll setups display the employer PAYE reference)

If you need to re-enter it, copy it from the HMRC letters rather than typing it from memory. A single missing digit, space, or slash can trigger an error when you input the number into an online form.

Tip for busy teams: include the ERN in a single internal admin tab (for example: “HMRC references”), alongside the company name, the scheme name, and where you can read it (letter date / document). It’s a small policy that saves time later.

Quick table: ERN vs other common HMRC references

These are different types of tax references, and mixing them up can create admin delays, especially in multi-entity companies where employement records sit across more than one system.

Can a business have more than one ERN?

While uncommon, a business can have more than one ERN. 

You can be assigned a unique ERN for each scheme if you manage different PAYE schemes across multiple locations.

You should manage and keep these different ERNs safe to use the correct one as required.

What should you do if you’ve lost your ERN?

This happens a lot, especially when employment admin moves between people.

Start with these checks:

• search for HMRC letters about “PAYE” or “employer reference”

• check older payroll documents (P45, P60, P11D, payroll reports)

• look for any onboarding or admin docs where you store company numbers

A quick way to recover it is to check the latest letters or emails from HMRC and compare the numbers you see. If you find more than one reference, make sure you’re using the correct employer PAYE reference for the right PAYE scheme.

If you still get an error when you input it into a form, double-check spacing, the slash, and any missing characters. It may also help to keep a short internal note in your admin tab that includes the employer name, the reference number, and where it was found (letter date, document, or saved record). This simple policy avoids repeat searches over time.

If you can’t find it, it’s worth confirming you’re registered correctly and following HMRC’s official steps for employer registration (that’s also how you receive your employer PAYE reference).

When might you not have an ERN?

In most cases, you only have an ERN if you’re running PAYE.

You might not have one if:

• you don’t have employees yet

• you pay workers through an agency (the agency runs payroll)

• you only work with self-employed contractors who invoice you (and you’re not operating PAYE for them)

Some businesses assume they don’t need PAYE if nobody earns “enough”. A common reference point is the National Insurance lower earnings limit: for 2025/26 it’s £125 per week / £542 per month. For the most current figures, use HMRC’s published rates and allowances.

How can payroll software help you keep track of your ERN?

If you operate under the PAYE payroll scheme, your ERN is one of those key references you’ll want to keep close, just like any other tax and legal identifier your company relies on. The simplest way to avoid last-minute digging is to set a clear internal policy for where it’s stored and who owns it.

Using a modern payroll software, you can keep core employer details in one place and ensure they’re reused consistently across payroll documents and tax forms linked to PAYE, instead of living across inboxes, folders, and spreadsheets.

That typically means fewer copy/paste errors, less admin churn, and less time spent chasing information, especially for growing companies where responsibilities move between people.

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