As an employee you should already have a National Insurance Registration Card, with your National Insurance (NI) number printed on it.
Here's some useful information about your card and number:
1. Keep your card in a safe place
2. If you lose your card ask the National Insurance Office for a new one right away
3. You don't need to re-register if you change jobs just let your new employer know that you already have a National Insurance number
4. Your number remains the same even if you change jobs several times
If you need further details why not check the Information Zone for our FAQ and Glossary.