Forgotten Savings Surge Nearly Sixfold to £217M as Britons Lose Track of Cash

The amount of forgotten money sitting in dormant cash ISAs at National Savings and Investments (NS&I) has surged nearly sixfold to more than £217M ($286M), as tens of thousands of Britons lose track of savings they put away years ago.

Newly released NS&I figures show the sum trapped in these dormant ISAs has climbed from £36.7M ($48M) in 2020/21 to more than £217M in 2024/25. The number of dormant accounts rose nearly fivefold over the same period, from 8,621 to 42,973, with each now holding an average of £5,061 ($6,680).

The money earns very little where it sits. Matured or discontinued ISAs of this kind typically pay about 0.25% interest, against up to 5% on the top-paying easy-access accounts elsewhere. On an average balance of £5,061, 0.25% amounts to roughly £13 ($17) a year. Transferring a dormant balance to another cash ISA preserves its tax-free status, whereas withdrawing the money to chase a higher rate would lose it.

Why Dormant Accounts Are Rising

Part of the increase is down to the calendar. NS&I classifies an ISA as dormant once 15 years have passed since the holder last paid in or took money out, measured from the final transaction.

Cash ISAs were introduced in April 1999, so the earliest are now well beyond the 15-year mark. Those opened in the early 2000s are passing the threshold in large numbers, lifting both the count of inactive accounts and the sums held in them. House moves, name changes after marriage or divorce, and accounts opened for children who have since grown up all add to the total.

The pattern extends beyond ISAs. NS&I figures show £614M ($810M) is held across 1,117,000 postal-only accounts, which can be operated only by mail, at an average of just £550 ($726) each. Dormant ISA balances are funnelled into what NS&I calls its residual account, which the data shows now holds more than £650M ($858M).

NS&I's Bereavement-Payments Failure

The figures follow a separate problem disclosed by NS&I earlier this year, when it admitted an operational failure had left thousands of bereaved families unable to access hundreds of millions of pounds in savings belonging to relatives who had died. That failure led to the resignation of chief executive Dax Harkins, who was replaced on an interim basis by former HM Revenue and Customs boss Sir Jim Harra.

NS&I holds savings for more than 24 million customers, including over 22 million Premium Bonds holders. All deposits carry a 100% guarantee from HM Treasury, and dormant funds do not expire. Savers can reclaim them regardless of how many years have passed.

How to Trace a Lost Account

Savers who think they may have lost touch with an account can trace it free of charge. NS&I runs its own tracing service, and its records can also be searched through My Lost Account, a free service run jointly with UK Finance and the Building Societies Association that checks NS&I alongside dozens of banks and building societies in a single application.

Applicants need to supply details such as previous names, former addresses, and the approximate date an account was opened. The service is free, and NS&I says savers do not need to pay a third-party firm to find or reclaim money.

Premium Bonds holders can separately use NS&I's online prize checker to see whether they are owed any unclaimed winnings. NS&I says it handled 101,050 tracing requests in 2025 and reunited customers with £201.5M ($266M) in lost savings.

An NS&I spokesperson told The Telegraph: 'All money invested with NS&I is 100 per cent secure, backed by HM Treasury, and whether it's unclaimed Premium Bonds prizes or forgotten accounts, we want customers to be reunited with these funds.'