You will normally be sent a National Insurance (NI) number, which looks something like AB123456C, just before your 16th birthday.
If you have lost your NI number you should contact HM Revenue and Customs. You can either complete the online form on the HMRC website, or call the National Insurance enquiries helpline on 0300 200 3500 (lines are open 8am to 5pm, Monday to Friday).
Even if you are working part-time or earning a low wage – perhaps too low to pay NI contributions – you must still have an NI number to get a job.
You will not be allowed to register for work at an employment agency without paper evidence of your NI number, which the agency must photocopy and return.