£217m left forgotten in cash ISAs

More than £217m is currently held in dormant National Savings and Investments (NS&I) cash ISA accounts, according to figures released following a freedom of information request by the Telegraph.

Over the past four years, the number of forgotten accounts has risen almost five-fold, with an average of £5,061 held in each inactive account.  

Between 2020-21 and 2024-25, the number of dormant cash ISAs accounts climbed from 8,621 to 42,973, while the total amount held in them increased from £36.7m to £217.5m.

The Treasury-backed savings provider introduced its direct ISA accounts in 2006 and classifies them as ‘dormant’ when no transactions have taken place for 15 years. Under NS&I's procedures, account statements are no longer issued when correspondence is repeatedly returned undelivered or when these 15 years have passed without customer contact.

Although dormant accounts continue to earn interest at their usual rate, there is a risk that the money could eventually be transferred to NS&I's residual account. This holds balances from products that have matured or been withdrawn and typically pays a much lower interest rate of around 0.25%.

The figures also revealed that £614m was sitting in 1,117,000 postal-only savings accounts, which can only be managed through physical mail.

Savers with these investment accounts have missed out on average around £550 of potential interest.

The findings follow an admission by the state-owned savings provider in March 2026 that it had misplaced nearly £500m of customers' savings, potentially including cash ISAs. The issue came to light following an investigation by The Telegraph into delays in releasing funds to bereaved families.

The controversy ultimately resulted in the departure of Dax Harkins, who resigned after three years as NS&I's Chief Executive.

What is an ISA?

An ISA, or ‘Individual Savings Account’, is a scheme that allows anybody to hold cash, shares and unit trusts free of tax on dividends, interest and capital gains. Essentially, it’s a savings account that you don’t pay tax on.  

A cash ISA is a tax-free savings account that allows people to save cash without incurring income tax on interest.  

You can save up to £20,000 each tax year across ISAs and receive tax-free interest payments, so when the value of your cash ISA increases, you get to keep all of it tax-free. Though it's important to note that from 6 April 2027, the annual cash ISA allowance will fall to £12,000 for those under 65, while those aged 65 and over will continue to be able to save up to £20,000 each year.

While there is a £20,000 allowance in place for how much you can put in a year, there is not a cap on how much you can accumulate in an ISA over a lifetime.  

If you want to find out more, why not give us a call on 0333 323 9065 or book a free non-committal initial consultation with one of our chartered advisers to see how we can help.

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The Financial Conduct Authority (FCA) does not regulate cash flow planning, estate planning, tax or trust advice.