Meaning of Last Letter of UK National Insurance Number (Your NINO)

Updated on July 27, 2020
Beth Eaglescliffe profile image

I write about employment issues, ways to earn money and how to get best value when spending it.

Every worker in the UK has a unique National Insurance number.
Every worker in the UK has a unique National Insurance number. | Source

Meaning of NI Number and Letter Combination

Your UK National Insurance number may look like a random string of numbers and letters, but there is a meaning to the pattern.

An NI Number (or NINO) Has Three Parts

  1. The first two letters are known as the prefix letters.
  2. These are followed by six numerals.
  3. Finally, there is a single suffix letter at the end of the string.

Your NINO Stands in for a UK Identity Card

Each person of working age is issued with a unique NI number and letter combination. This sequence is individual to you and remains the same whether you move house or get married. The number is your personal identifier and remains the same throughout your life.

The United Kingdom has no statutory personal identity card or ID document. In most cases your NINO is not sufficient by itself to prove your identity, but may be used in combination with other documents to establish residence and tax status.

How Britain Really Works is a good guide to the formalities of working in the UK. Once you are over sixteen years of age and start paid work in the UK you are automatically issued with a National Insurance number (also called a NI number or NINO). A person’s NI number is very important as it is used to link employment records with social security benefits and tax payment records.

What Are National Insurance Contributions?

National Insurance (NI) is paid by everyone working in the UK who earns over a certain amount. The payments are recorded centrally and they determine eligibility for all health and social security benefits including the State Pension.

National Insurance is paid together with income tax through PAYE (pay-as-you-earn). NI is deducted from gross wages before they are received by an individual employee.

Unique British National Insurance Number

Fictitious Example
Meaning Behind It
Prefix letters
originally linked to location
Middle numbers
random sequence
Suffix letter
shows season for audit

Prefix Letters Were Linked to Location

When the system first started, the two prefix letters (at the beginning) were intended to represent the geographical location of the individual holding that National Insurance identity. However, the system was flawed because some areas of the country were more populous than others. Thus the number of unique combinations using the same two prefix letters was used up more quickly in some areas. So the system was changed.

The NI prefix letters that are currently used are not randomly generated. There is no publicly available information on how these new number combinations are created. The UK government uses the Freedom of Information Act 2000 to withhold details of how exactly the numbers are chosen.

Middle Numbers Are a Random Sequence

The six numbers contained within each unique NI number are a random sequence of numerals. These middle numbers are used by government departments like HMRC (Her Majesty’s Revenue and Customs) and the DWP (Department of Work and Pensions) as a unique identifier for each person. These, used in tandem with the prefix and suffix letters, give an individual identity number to every working person in the UK.

How Is Suffix Letter Determined?

The lone suffix letter (at the end) is a leftover identifier which relates to the manual collection of national insurance payments. Prior to electronic record-keeping, a physical record of National Insurance payments was kept. Every employer had to literally buy a physical stamp and stick it onto a National Insurance card. There was one of these NI cards kept for each employee. The stamp proved that an employer had paid the appropriate NI contribution for that particular employee for that week.

There were millions of these cards and they needed to be checked annually by the government. In order for the checking to be spread evenly over each twelve-month period, every NI card was linked to a particular month. This was signified by the suffix letter at the end of the National Insurance number. This ensured that during each three-month period, only one quarter of the nation’s National Insurance cards were being processed by the relevant government department.

Examples of Suffix Letters and What They Meant

  • For example, a card which had a suffix letter "A" would be sent for checking at the beginning of March.
  • The letter "B" was the designation for cards to be examined at the beginning of June.
  • The letter "C" showed that the card should be ready for inspection at the start of September.
  • The suffix "D" was for the final quarter of the year and was for cards to be checked in December each year.

Today, the Suffix Letter Is Irrelevant—But Still Necessary

With electronic processing and instant transfer of payments, the suffix letter of the U.K.’s National Insurance number has become irrelevant. However, it is still necessary to use it, as without the full unique combination, your National Insurance number will not be accepted as valid.

Non-UK Passport Holders and National Insurance

Non-UK passport holders will not be issued with a National Insurance number unless they are resident in the UK for study or work purposes and hold an appropriate study or work visa.

It is not possible to get a UK NI number if you are only on vacation in the UK. It is illegal to obtain work in the UK without the relevant visa documents and work permit.

How to Get a UK National Insurance Number

Frequently Asked Questions

Does the UK Use the Suffix Letter on New NI Numbers?

Yes. A suffix letter is an integral part of all UK National Insurance (NI) numbers. There was an instance some years ago where a batch of numbers were mistakenly issued with the last letter missing. The issue of new numbers was temporarily put on hold, as fraud was suspected. This is now resolved, and you should contact HMRC if you think your National Insurance number is incorrect.

All legitimate NI numbers are made up of a two-letter prefix followed by six numbers and then a single letter suffix.

Where Can I Find My National Insurance Number?

If you are employed, you can find your NINO on every pay slip. If you are self-employed take a look at your latest tax return. Your National Insurance number is at the top of the first page of the form.

If you have recently left work, your P45 and P60 forms (completed by your employer) will show your NINO. If you do not have any of these documents, you need to contact HMRC for help.

Where Can I Find My National Insurance Number Online?

Your National Insurance number can be found on a letter from the Department for Work and Pensions (DWP) or on your bank statement if your pension is paid into your bank account.

You can also search for it on the UK government's website.

In the UK, it is compulsory to make National Insurance contributions.
In the UK, it is compulsory to make National Insurance contributions. | Source

Does Having an A in Your NINO Mean You Could Be Called for Army Service?

No. The letter at the end of your National Insurance number does not place you on any list for conscription to the armed forces. Britain abolished National Service in the 1960s. The last conscripted service personnel finished their terms of duty in 1963. Since then anyone joining the UK's army and navy do so of their own free will.

Do Siblings Have the Same National Insurance Number?

No. Each person has a unique and individual NINO. If your National Insurance number is similar to a brother or sister that is just coincidence. NI numbers are issued depending on when a person joined the workforce and where they were living at the time.

If you are worried there has been a mix-up between you and a sibling, especially if you have similar names, contact HMRC. It's important that the payments deducted from your salary each month for National Insurance are credited to your record and not to someone else's. If the record is incorrect it will affect any state benefits or pension rights you may have in the future.

Do National Insurance Numbers Expire?

No, your National Insurance number never expires. Each NINO is a unique identifier and may only be used by the person to whom it is issued. It continues to be attached to your personal data files, even after you have died.

Does a NINO Reveal Your Age?

No, your NINO doesn't give away how old you are. This means it cannot be used to prove that you are over 18 or to meet any other age-related requirement. The numbers and letters that make up your NI number are a random sequence that reveal nothing about your location, age or employment status.

What is NINO? Who Pays National Insurance?

For accurate and up-to-date information about applying for a UK National Insurance number and current contribution levels, you should refer to Her Majesty's Revenue and Customs (HMRC) website.

Your National Insurance number is printed on all your payslips as well as on all communications to you from the tax office. If you have lost your NINO and cannot remember it, you will need to complete Form CA5403 on HMRC's website.

National Insurance (NI) numbers are as British as red London buses.
National Insurance (NI) numbers are as British as red London buses. | Source

Do You Know Your NINO?

Do you know your National Insurance number off by heart?

See results

How Does BREXIT Affect My National Insurance Number?

BREXIT is short for Britain Exiting (leaving) the European Union and means that from 2021 there is a change in relationship between the UK and the rest of Europe.

There will no longer be freedom of movement for European nationals to the UK. Both EU nationals and overseas visitors will need an employment visa to work in the UK. Current NI numbers will be unaffected, but there could be a new numbering system to identify migrant workers.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.


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