BRITISH savers could be losing thousands of pounds in interest by sticking with outdated Cash ISA accounts, new analysis reveals.
Millions of UK savers could be missing out on as much as £13,000 in interest by failing to review their Cash ISA rates, according to new analysis from personal finance platform Investing Insiders, which has a tool to find the best rates.
The research highlights a significant gap between the best and worst Cash ISA rates currently available. While top accounts are offering returns of around 4.5%, some older accounts continue to pay as little as 0.75%.
Over time, this gap can have a dramatic impact on savings.
Analysis shows that a £20,000 balance growing at 0.75% would reach approximately £21,551 after 10 years. At 4.5%, the same amount would grow to around £31,000, a difference of nearly £10,000 in interest alone.
Even savers earning what appears to be a reasonable rate are still falling behind. The average Cash ISA rate currently sits at around 2.9%, which would grow £20,000 to roughly £26,600 over the same period. That is more than £4,500 less than the best available deals.
When applied to the average UK saver, the impact becomes even more pronounced.
HMRC data shows that the average Cash ISA balance is approximately £26,900. Based on current rates, the difference between the worst and best accounts could cost savers close to £13,000 in lost interest over ten years.
Across the UK, around £360 billion is currently held in Cash ISAs. If these balances were moved from average rates to the most competitive accounts, savers could collectively earn nearly £6 billion more in interest each year.
A quick check today could make a meaningful difference
Antonia Medlicott, Founder & MD at London-based Investing Insiders, urged Brits to shop around for the best Cash ISA rates.
She added: “There is a common assumption that once your money is in an ISA, the job is done. But that is not the case. While ISAs protect your savings from tax, they do not guarantee a competitive return. The gap between rates may not look dramatic at first glance, but over time it compounds into something significant.
“For many savers, this could mean thousands of pounds in missed interest. What we are seeing is what I call the ‘ISA loyalty penalty’. People stay with the same provider for years, often assuming they are getting a fair rate, when in reality they could be earning far more elsewhere.
“The good news is that switching is usually straightforward, and in many cases the new provider handles the transfer. A quick check today could make a meaningful difference to your savings over time.”
Anita Wright, Chartered Financial Planner at Ribble Wealth Management, said inflation is eating away at savings.
She added: “Over the last decade, cash has consistently struggled to keep pace with inflation. Even where savers have achieved what appears to be a reasonable rate, the real return after inflation has frequently been negligible or negative. So whilst switching from 0.75% to 4.5% looks compelling on paper, the more important question is whether the capital is genuinely preserving purchasing power over time.
“There is also a practical consideration. Achieving the best rates typically requires regular switching, monitoring the market and managing transfers, which can be time consuming and not always worthwhile for modest balances or short-term savings.
” In reality, many people do not review their Cash ISA rates regularly not just due to lack of awareness, but because of inertia, perceived complexity and the effort involved. In terms of education, I would suggest the focus needs to shift slightly. It is not just about encouraging people to chase the highest rate, but about helping them understand the purpose of cash within their overall financial position.”
People rarely shop around
Ross Lacey, Director & Independent Financial Adviser at Rayleigh-based Fairview Financial Management, said it is better to invest rather than have money in cash.
He added: “The rates now, aren’t going to be the same in one year, let alone 10. A better comparison is to look at the difference between leaving money in a ‘top performing’ Cash ISA versus investing across a broad range of company shares over 10 years.”
Rohit Parmar-Mistry, Founder at Burton-on-Trent-based Pattrn Data, said banks are intentionally giving uncompetitive rates.
He added: “The ISA ‘loyalty penalty’ is basically a tax on inertia. Banks know most people do not review savings rates unless they are forced to, so the easy money is leaving legacy accounts to rot at sub-1% while headline rates do the marketing.
“Yes, people rarely shop around. Life gets in the way, and the process still feels fiddly: multiple accounts, provider logins, and fear of moving money to the wrong place. Education helps, but frictions and defaults matter more. Make switching as simple as porting a mobile number, and prompt people at predictable moments such as an annual statement or rate drop maturity.
“I would like to see clearer nudges and better disclosure: show the gap versus best-in-market and what it costs in pounds, not percentages. If a provider cuts your rate, they should have to tell you what a comparable easy-access ISA pays elsewhere.”
Photo by Philip Veater on Unsplash.
