Your National Insurance Number is your own personal account number. It is unique to you and you keep the same one all your life.  As an expat, you'll need one when working. You can start work without one; however, you'll need to apply for one straightaway.

The National Insurance Number is sometimes referred to as a NI No or NINO.

When and how to get a National Insurance Number

As an expat, you will be required to apply for a National Insurance Number when starting work or setting up as self-employed. Plastic National Insurance cards are no longer issued; however, if you have the right to work in the UK, you will need to telephone Jobcentre Plus on Tel 0845 600 0643 to arrange to get one. All National Insurance Numbers are now notified by letter.

Lines are open 8.00 am to 6.00 pm Monday to Friday and are normally less busy before 9.00 am. They may require you to attend an 'Evidence of identity' interview. See below for more information.

More about UK tax.

What happens when you apply for a National Insurance Number

Jobcentre Plus will arrange an 'Evidence of Identity' interview for you or send you a postal application. If relevant, they will confirm the date, time and location of your interview and what information and supporting documentation you need to support your application.

What to expect at the 'Evidence of identity' interview

The interview will usually be one-to-one (unless you require an interpreter). You will be asked questions about why you need a National Insurance Number, your background and your circumstances.

You will also have to prove your identity. Bring as many 'identity documents' (originals, not photocopies) as you can to your interview.

Examples of documents which count are:

■ valid passport (UK or foreign)
■ national identity card (UK or foreign)
■ residence permit or residence card including biometric immigration residency documents
■ full birth or adoption certificate
■ full marriage or civil partnership certificate
■ driving licence (UK or foreign)

If you don't have any of these - or other - identity documents you still must go to the interview. The information you are able to provide might be enough to prove your identity. During the interview a National Insurance Number application form will be completed and you will be asked to sign it.

What happens next?

If you were asked to provide additional information you will need to do this by the agreed date. Jobcentre Plus will write and let you know whether your application was successful and what your National Insurance number is. Tell your employer your National Insurance Number as soon as you know it. Do not share your National Insurance number with anyone who does not need it as this might help someone to steal your identity.

Keep the letter telling you what your National Insurance number is safe as it is a useful reminder of your number. However, the letter on its own cannot be used to prove your identity and you do not need it to apply for a job or before starting to work. It's the National Insurance Number itself that's important.

If you've lost or can't remember your National Insurance number or lost your National Insurance number card

If you've lost or can't remember your number, you might be able to find it on official paperwork such as:

■ your P60 (end of year tax statement, given to you by your employer). P60 information.
■ a payslip
■ a copy of your annual Self Assessment tax return
■ other official correspondence

If you still can't find your number, you can ask HMRC to confirm it by:

■ completing and returning form CA5403 Your National Insurance number
■ contacting the National Insurance Registrations Helpline on Tel 0845 915 7006 (lines open 8.30 am to 5.00 pm Monday to Friday)

Please note that HMRC cannot confirm your National Insurance number by telephone - they will write to you instead.

For more information about UK tax, please refer to our finance and business section.