Finding Your NS&I Holder's Number

Your NS&I holder's number is the reference that identifies you and your savings with NS&I. It is 11 digits long and starts with an 11, 21, 31 or 41¹. It is not your National Insurance number, and it is not the same as an account number you might use to pay money in.

If you have lost it, you can get a reminder online using your name, date of birth and postcode, or find it on any letter NS&I has sent you since you registered for the online service². If you hold Premium Bonds, you can also log in to the online service and check your Premium Bonds account page, or call NS&I for a replacement Bond record³.

This page covers what the number is, how it works with your password, where to find it, how to prove your identity when NS&I asks, what to do if you have several holder's numbers, and how to keep the account safe.

What an NS&I holder's number is and what it covers

The holder's number is the thread that runs through everything you hold with NS&I. It identifies you, not a single product, so it is the reference you quote when you call, write or log in. NS&I issues it when you first register, and it appears on correspondence from that point on².

It is easy to confuse with other numbers. A National Insurance number is a different thing entirely: it records your National Insurance contributions and the tax you pay⁸. From 6 April 2027, ISA managers will be required to obtain a National Insurance number from all investors who are eligible to have one, which is a separate requirement from anything NS&I uses to identify your savings⁹.

NS&I is the UK government-owned savings bank, and it also administers schemes on behalf of the Treasury, such as the Mortgage Guarantee Scheme⁶. That breadth is why the holder's number matters: it is how NS&I matches you to every account, bond or holding in your name, including Premium Bonds.

For Premium Bonds specifically, NS&I treats all Bonds held under one holder's number as a single holding¹². That matters for how prizes and holdings are counted, and it is the reason merging duplicate numbers is worth doing if you have more than one.

Your NS&I number and password: how online and phone access works

When you join NS&I, you receive an NS&I number and create a password to access your account¹¹. The two work together: the number identifies you, the password proves it is you.

If you forget the password, you can reset it online using your NS&I number and surname, with an automated call to your phone². If you forget the number itself, you can get a reminder online using your name, date of birth and postcode². You will find your NS&I number on any letter you have had from NS&I since you registered for the online banking service².

There is one limitation worth knowing. If you have an NS&I number, you can only use it to check whether you have won a prize in the prize checker app, not on the website¹. The app and the website are not interchangeable for that purpose.

Once you have registered, applying for a new investment online and by phone is quicker, because NS&I already holds your details¹³. Some accounts are managed online or by phone only: the Direct Saver, for example, is applied for and managed that way¹⁴.

Where to find your holder's number if you have lost it

There are several routes, and which one suits depends on what you still have.

• On paper: any letter from NS&I since you registered for the online service carries the number².
• Online reminder: enter your name, date of birth and postcode to get a reminder of your NS&I number².
• Premium Bonds: log in to the online service and check your Premium Bonds account page, or call NS&I for a replacement Bond record³.
• Tracing an old investment: the Tracing Service can help. You can download and print a paper form and post it to Tracing Service, NS&I, Sunderland SR43 2SB, or apply online with My Lost Account or through the online form¹⁵.
• Forgotten savings pots generally: the My Lost Account service can help you search for forgotten savings pots from banks and building societies, including NS&I¹⁶.

If you are tracing something older, NS&I's closed products page explains what happens to accounts that are no longer open, and the tracing lost NS&I savings guide sets out the process in more detail.

Proving your identity to NS&I: documents by age and where you live

NS&I is required by law to check your identity and address when you apply to invest or register for the online and phone service, and possibly at other times to keep records updated¹⁸. What you need to send depends on your age and where you live.

For UK savers aged 18 and over, accepted identity documents include a copy of your current valid full passport, a GB or Jersey photocard driving licence, a certified Guernsey, Isle of Man or Northern Ireland photocard driving licence, an Armed Forces ID card certified by a commanding officer, a Home Office UK biometric residence permit, a firearms certificate or shotgun licence, an Electoral Office for Northern Ireland identity card, an HMRC tax document less than one year old (P45s and P60s are not acceptable), or a letter from a benefits agency confirming benefits or state pension issued in the last 12 months¹⁸.

Documents must show the issuing organisation's name and contact details. If the document type is not obvious, NS&I may ask for a certified translation into English¹⁸.

Who can certify copies of your documents

Certified copies need a set wording written on every page in English: "I certify that this a true and complete copy of the original [type of document] belonging to [your name]." Each page must be signed and dated, and include the certifier's full name, occupation, work address, daytime telephone number, official stamp where available and professional registration number if they have one¹⁸.

Overseas certifiers use a slightly different wording: "I certify that this is a true copy of the original [type of document] belonging to [your name]." written on the copied document, signed and dated, with the certifier's occupation or capacity stated¹⁸.

In Northern Ireland, a local Jobs & Benefits office can check original documents and make certified copies with their office stamp, which is a route used for Maternity Allowance evidence and shows the kind of certification accepted there¹⁹.

Several holder's numbers? Merging them into one

It is possible to end up with more than one holder's number, particularly if you have held NS&I products at different times or opened accounts in different ways. NS&I can merge your accounts, and there is a dedicated process for it²⁰.

Merging matters most for Premium Bonds, because NS&I treats all Bonds held under one holder's number as one holding¹². Two holder's numbers mean two separate holdings until they are merged.

For your security, NS&I cannot disclose or change personal information without the account holder's signature²⁰. If you are taking control of accounts without using the online service, you need to write to NS&I including which accounts you have, your holder's or account number, your name, address and date of birth, your signature, and the signature and details of a witness²¹.

Some NS&I accounts can be held jointly, which affects how holdings are counted. A Direct Saver can be opened in your own name or jointly with one other person¹⁴. Half of the balance in a joint Direct Saver counts towards each account holder's personal holding limit²². Green Savings Bonds can be invested jointly with one other person²³. If one account holder of a joint account dies, the surviving account holder gets ownership of the account²³.

Keeping your NS&I number and account safe from fraud

Your holder's number is a piece of personal information, and it is worth treating it that way. NS&I's own security promise is that it will refund any money taken out of your account fraudulently as long as you have taken reasonable care to keep your account safe²⁴.

The detail behind that promise is in NS&I's key documents. If you did not authorise a payment from your account, NS&I will normally return the account to the position it would have been in, including missed interest or prizes, unless you did not take reasonable care or did not report lost or stolen security details promptly. There is no refund where fraud by the customer is suspected²⁵.

A few practical points follow from the rules:

• To reset security details, you need your account or holder's number to hand, as well as the type of account you hold².
• NS&I cannot disclose or change personal information without the account holder's signature²⁰.
• If you are asked for your holder's number by someone who contacted you first, treat it as a scam until you have verified it independently. The savings and fake bond scams guide explains how these approaches work.

Identity theft is a wider problem, and the Information Commissioner's Office publishes guidance on what to do if it happens²⁶. If you are in England or Wales and the fraud relates to NHS services, there is a separate reporting route²⁶.

Is money held with NS&I protected?

NS&I is the nation's savings bank, backed by the UK government⁵. It is the UK government-owned savings bank⁶. That backing is the key difference between NS&I and an ordinary bank or building society.

NS&I is backed by the Treasury and is therefore not covered by the Financial Services Compensation Scheme. Instead, 100% of all NS&I savings are fully protected⁷. That is a stronger position than the FSCS cap that applies to banks and building societies, where protection is limited to £85,000 per person per firm⁷.

The distinction matters if you hold large balances. The NS&I accounts guide explains how the Treasury backing works across different NS&I products, and the FSCS protection guide covers the limits that apply elsewhere.

If something goes wrong with an NS&I account, NS&I publishes its complaints process¹². The Financial Ombudsman Service can look at complaints that are not resolved, and free, impartial help is available from MoneyHelper.