How to Find an Old Bank Account Number in the UK

This guide explains how to recover the account details for a UK bank or building society account you know about but cannot find the number for. It is not financial advice.

There are two different problems hiding behind "I have lost my old bank account". One is that you know the bank and the account exists — you need the number, for a tax return, a claim, an inheritance, a pension trace or a form that will not accept anything else. The other is that you do not know where the money is at all.

This guide covers the first. If you are not sure which institution held the account, or whether one exists, start with our guide on tracing lost savings accounts, which covers the free My Lost Account service.

Nobody needs to pay a fee for any of this. Every route below is free.

In rough order of speed:

1. Your own paperwork. Statements, a chequebook, a paying-in book, old payslips, a P60, a tax return, or a standing order set up from another account — any of these carry the number.
2. Ask the bank. With proof of identity, a bank can give you the details of an account it holds in your name, including a closed one within its retention period.
3. A data subject access request. A free legal right under UK data protection law, answered within one month, and the route that works when a phone line will not.
4. My Lost Account, if the institution has merged, rebranded or you are unsure.
5. The Dormant Assets Scheme, if the account has sat untouched for 15 years.

The account number is on more documents than most people expect. Worth checking before anything else:

• Old statements, paper or in a downloads folder. A single PDF is enough.
• A chequebook or paying-in book, which shows sort code and account number on every leaf.
• Payslips and P60s, where employers often print the last four digits — enough to identify the right account when you speak to the bank.
• Another bank's records. If you ever transferred money to the account, made a standing order, or received one from it, the payee details sit in the other bank's transaction history. This is the most commonly overlooked route, and it usually shows the full number.
• Self Assessment returns, if interest was declared, and ISA paperwork, which records provider and account references.

A bank can tell you the details of an account held in your name once satisfied you are the account holder. Expect to prove identity to the standard used to open an account: photo ID, proof of address, and often previous addresses, dates and approximate balances.

Two points people get stuck on:

A closed account is not gone. Anti-money-laundering rules require records of a customer relationship to be kept for at least five years after it ends, and most banks retain longer. A branch or telephone team can usually confirm details of an account closed within that window.

The brand may not exist any more. UK banking has consolidated heavily. If the institution was absorbed, the successor holds the records — Registry, merger and rebranding history is exactly what My Lost Account exists to navigate.

If the phone line goes nowhere, this is the route that has legal force behind it.

Under Article 15 of the UK GDPR, you can ask any organisation for a copy of the personal data it holds about you. A bank's answer will include account details, and typically statements and correspondence.

• It is free.
• The response is due within one month, extendable by up to two further months for complex or multiple requests, provided you are told within the first month.
• It can be made in writing or by email, and does not have to use a specific form. Say clearly that you are making a subject access request, identify yourself, and describe what you are looking for — an account held at a named branch between certain years, for example.

If the bank does not respond, the Information Commissioner's Office handles complaints about data rights, separately from the Financial Ombudsman Service, which handles complaints about the banking itself.

My Lost Account is the free, central tracing service backed by UK Finance, the Building Societies Association and NS&I. It searches participating banks, building societies and NS&I products at once, which is why it is the right tool when a name has changed or your memory of the institution is uncertain.

Published timescales are around three months for banks and building societies, and around one month for NS&I. Online applications are processed faster than postal ones.

An account with no customer-initiated activity for 15 years can be classified as dormant under the Dormant Bank and Building Society Accounts Act 2008, and the balance transferred into the Dormant Assets Scheme.

Interest credited by the bank does not count as customer activity, so an untouched savings account can reach dormancy while still growing.

The money is not lost. Reclaim Fund Ltd, the FCA-regulated body that runs the scheme, remains liable for reclaims in full and without a deadline. You still start at the bank, which retains the record of the account and routes the claim.

The route changes: you are asking as a personal representative, not an account holder. Banks will want the death certificate and evidence of your authority — a grant of probate or letters of administration — before releasing details, though most will confirm the existence of an account and a date-of-death balance on sight of the death certificate.

My Lost Account accepts searches from executors and administrators, and NS&I holds a separate tracing route covering Premium Bonds and other products, where unclaimed prizes have no expiry date.

Firms advertising to reunite you with lost accounts for a percentage of what they recover are selling access to free services. My Lost Account costs nothing, a subject access request costs nothing, and a reclaim from the Dormant Assets Scheme costs nothing. Before paying anyone, check the FCA Register — and be sceptical about handing identity documents to an unregulated intermediary. For the general shape of the risk, see our guide on protecting your credit file from identity fraud.

Looking for more on this topic? Browse all our savings guides.

This guide draws on the following legislation and official sources:

• Dormant Bank and Building Society Accounts Act 2008
• Dormant Assets Act 2022
• Data Protection Act 2018
• Information Commissioner's Office — your right of access
• FCA Financial Services Register

Free, impartial money guidance is available from MoneyHelper, the government-backed service run by the Money and Pensions Service.

Related: Lost Track of Old Savings Accounts | Child Trust Fund Matured: How to Access It | All savings guides.