Tens of thousands of savers are missing out on an average £5,000 as new data released by National Savings and Investments (NS&I) reveals the number of dormant accounts has skyrocketed.
Over £217m is being held in forgotten cash Isa accounts opened with the government-backed bank – up nearly five times from four years ago, when the figure sat at £36.7m.
NS&I, which also administers Premium Bonds, considers an Isa account to be dormant after 15 years of inactivity, measured from the last time the owner made a transaction.
There were 42,973 of these accounts in 2024/25, the data obtained by The Telegraph shows, up from 8,621 in 2020/21. These hold an average £5,061 each.
Earlier this year, NS&I revealed that it had mistakenly withheld £367m from thousands of bereaved families due to an “operational failure” to trace the savings accounts of many bereaved customers.
Around 34,000 estates were affected by the issue, the bank has said, with the compensation process expected to be completed in the first half of 2027.
The issue led to the resignation of former NS&I chief executive Dax Harkins, who had been in the post for three years.
The newly-released figures also reveal that £614m is being held in 1,117,000 postal-only savings accounts, which are only manageable through physical mail. These hold an average £550.
Dormant Isas held with NS&I will continue to accrue interest, but typically only at around 0.25 per cent due to being matured or discontinued products.
These accounts will go into the NS&I’s residual account, which the figures show currently holds more than £650m.
This means savers could be missing out on much more competitive savings rates, with banks offering as much as 5 per cent interest in the current market.
An NS&I spokesperson said that the bank received 101,050 tracing requests in 2025, reuniting customers with £201.5m through its own tracing service.
They added: “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.
“We provide information online and through our call centre on how to do this. We also regularly publicise details of unclaimed prizes and encourage customers to use our prize checker, to register to have Premium Bonds prizes paid directly into their bank account, update their contact details, and use our tracing service to track down lost accounts.”
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