CA5403 - Your National Insurance number
Before starting to complete the form, save it to your own computer.
- Form URL
How to get written confirmation of your National Insurance number if you can't find it.
The online version of this form has been temporarily withdrawn.
You can complete the form on screen, print it, and post it to HM Revenue and Customs (HMRC).
If you have problems opening the form, find help by following the link below 'Get help viewing PDFs' or use this version of CA5403. You'll have to print this version and fill it in by hand.
Whichever version you choose please read the factsheet first. You'll find it under 'Help and guidance relating to this form' in the next section.
- How to get written confirmation of your National Insurance number if you can't find it
Help and guidance relating to this form
- Form URL
Applying for a National Insurance number
How to get a National Insurance number, when you'll need one, what to do if you don't receive it or forget or lose it
Help with PDF files
PDF is a file format that lets you view and print a document in a style which matches the look and feel of the paper version - including fonts, colours, images and layout.
To view these documents you need to use a PDF viewer such as Adobe Reader.
Forms in alternative formats
If you would like an HMRC form in large print, Braille or another alternative format, please contact the relevant HMRC helpline - see the link below.