National Insurance numbers on ERS returns

The format

An NI number is 2 letters, 6 numbers and 1 letter, for example QQ123456C (QQ numbers are only used in examples). Write it in capitals with no spaces.

If an employee has no NI number

HMRC's guidance allows an alternative reference, only on the ERS return and only in exceptional cases. It is 9 characters:

• TN;
• the employee's date of birth as DDMMYY, for example 080403;
• a reason letter: X if under 16, Y if they have applied for an NI number and are waiting for it, Z if they have never been liable to UK National Insurance contributions.

For example TN080403Y. This reference is not an NI number and should not be used anywhere else.

What the checker does

It removes spaces and makes letters capitals, rejects numbers with the wrong shape, checks TN references, and warns about letter pairs HMRC never issues.

Your employees' NI numbers are checked inside your browser and are never uploaded.