When you are working your employer deducts a sum from your wages or salary as a NI contribution (you can check the amount from your pay slip). Your employer adds to this contribution.

Everybody in England needs a National Insurance Number. It’s used to record the national insurance contributions you have to pay when you are working. Your benefits depend on these contributions being recorded in your NI account.

Your right to Incapacity and Contributory Job Seekers Allowance, Maternity Allowance and Retirement or Widows Pension all depend on your NI contributions. You will also need your NI number if you claim other benefits like Family Credit, Income Support or Child Benefit.

The National Insurance Number can be applied for if you are:

1. recently been employed, or
2. actively seeking employment

If you're recently employed then, you don't have a problem. All you need to do is call the National Insurance Office and state you want to apply for the number. They will ask you a bunch of questions, mostly demographics, and will tell you to bring with you a letter from your employer stating your employment details. Your HR Manager would know what to write in the letter.
By the time when you don’t have your NI number, Inland Revenue provide you with a temporary number, and charge you with the highest tax level if you are paying tax.

Now, if you are actively seeking employment, here's what you need to do. If you registered with recruitment agencies, go back to them and ask for a letter stating that you registered with them. If you applied by mail to companies and they send you the "regret letter", keep this. If you appied for work online and received the "regret letter" online, print it. Gather at least 2 recruitment agency letters, or 2 mailed "regret letters", or at least 4 emailed "regret letters" or a combination of them. It goes without saying that these documentation should be from different companies or recruitment agencies.

Once you have these, and your passport (if non-EU, specially) or National Identity Card (EU citizens) make that phone call for your appointment to the National Insurance Office (which is actually a JobCentre office), where you will be interviewed. The employee there will be filling out the application form on your behalf and will ask you to sign to confirm the information written is correct. MAKE SURE YOU CHECK WHAT THE EMPLOYEE WROTE BEFORE SIGNING! (you could find the street name and first name misspelled, for example). Once you check and everything is okay, sign the form, and they will give you one page of it, kinda like a receipt. That form they give you, keep it. You can show that to a prospective employer as proof that you applied for the number, but NEVER give it out to anyone. That is YOUR property.

Contact your Jobcentre Plus office to find where you have to go to get your NIN:
Tel: 020 7712 2171 (9:00-17:00)
Fax: 020 7712 2386
Web: http://www.jobcentreplus.gov.uk

When you go to the local Social Security office, take at least 2 of the following documents with you as proof of your identity: - your passport - your marriage certificate - your original birth certificate - your full driving license.

It is open at 9am and close at 5pm. We advise you to go early, as it’s frequent to spend 2-3 hours there, mainly waiting. You will have to take a ticket, register when you are called, then wait to be called a second time to complete the form. You will have to answer to questions such as “how did you pay your ticket to come”, “do you work? ” or “do you go back to your country sometimes? ” (Write a text of about 30 rows!).

Now, after a few days you will receive a letter in the mail from the National Insurance office, stating your number already, although in letter format. No card yet. The card will come after about 4 -6 weeks after you receive that letter, but the number stated in that letter is your actual National Insurance Number already. Be careful with it, and don't readily give it out to anyone except to your employer, prospective employer, or recruitment agency (should they ask for it).

If you are employed, as soon as you are issued with a National Insurance Number (NIN), give the details to your employer for their records. This will ensure that any NI contributions you pay are credited to your National Insurance account.

Leaflet IR120 “You and the Inland Revenue” gives you full details of our complaint procedures. You can get this leaflet from any Social Security office, Inland Revenue Enquiry Centre, Citizens Advice Bureau and main libraries.