My payslip has the wrong National Insurance number. What should I do?

You have just received your first payslip from a new job, and while looking at the top box, you realise the National Insurance (NI) number is wrong. Maybe one digit is off, or maybe it is a completely bizarre format like TN123456F.

It is very important that you do not ignore this. Your NI number is your unique identifier for the UK tax system. Without it, HMRC does not know who is paying the tax.

Why is my NI number wrong?

There are usually only two reasons why a payslip shows the wrong NI number:

1. Human error by Payroll or HR

When your employer set you up on their payroll software, whoever typed in the details from your starter checklist or P45 simply hit the wrong key. A single typo (e.g., typing an 8 instead of a 9) means your payslip is now broadcasting data to a non-existent HMRC record.

2. It is a "Temporary" NI Number (TN)

If your NI number on the payslip looks like TN followed by your date of birth and a letter (e.g., TN 01 05 99 M), your employer has generated a Temporary National Insurance Number.

This happens if you did not provide an NI number when you started, or if you recently moved to the UK and are still waiting for your official number to arrive. The payroll software requires an NI number to run, so it generated a fake, temporary one just to force the calculation through.

How to fix it: The Step-by-Step Guide

Fixing this is entirely the responsibility of your employer's payroll department, but you have to initiate the fix.

Step 1: Contact your payroll team immediately

Do not wait until next month. Send an email to your HR or Payroll department immediately. Write something like:

"Hi Payroll, I noticed the National Insurance number on my recent payslip is incorrect. It is listed as [Wrong Number], but my actual NI number is [Correct Number]. Could you please update my payroll record and include this correction in your next FPS submission to HMRC?"

Step 2: Provide proof if asked

Payroll may ask for proof to ensure they don't make another mistake. You can provide a photo of your NI card, an old P60, an old payslip, or a screenshot from your HMRC Personal Tax Account.

Step 3: Check your next payslip

When your next payday arrives, check the payslip. The NI number should now be correct. When your employer submits that month's payroll to HMRC (via an FPS submission), the software will automatically flag the change in NI number to HMRC, and HMRC's computers will merge the disconnected records.

Will I have to pay extra tax?

If your NI number was wrong, it is very likely you were put on an Emergency Tax Code (like 0T or 1257L W1/M1). This means you probably paid too much tax on that first payslip.

Once payroll corrects your NI number, HMRC will finally be able to locate your previous tax history. HMRC will automatically send an electronic notice (P6) to your employer with your correct, cumulative tax code. On your following payslip, the payroll software will recalculate your tax for the year and automatically refund any tax you overpaid. (This will show up as a negative tax deduction on your payslip).

Frequently Asked Questions