The cash ISA is changing: why under-65s have one tax year left to use the full £20,000

One of the biggest shake-ups to British savings in years is now on the horizon, and it affects millions of people. The rules around cash ISAs, the most popular tax-free savings account in the country, are set to change. For anyone under the age of 65 who likes to keep a large chunk of money in cash, the window to act is closing. Understanding the change now could make a real difference to how much of your money stays free of tax.

The headline change is a cut to the amount that can be saved into a cash ISA each year. From 6 April 2027, the annual cash ISA allowance for savers under 65 will fall from the current £20,000 to just £12,000. The reduction was announced by the government in the Autumn Budget back in November 2025. It marks the first time in years that the cash allowance has been trimmed rather than frozen or raised.

Crucially, the change does not hit everyone in the same way. Savers aged 65 and over will keep the full £20,000 cash allowance and will not be affected by the reform at all. There is also a helpful detail for those approaching the milestone. During the tax year in which you turn 65, you are entitled to the full £20,000 allowance for that year.

What stays the same

It is important to be clear about what is not changing, because the headlines can cause unnecessary panic. The overall ISA allowance is staying exactly where it is, at £20,000 per year. What changes is only how much of that total can sit in cash for younger savers. The remaining £8,000 of the allowance will need to go into investing-style accounts instead.

In practice, that means the tax-free wrapper itself is not shrinking, only its cash portion for the under-65s. A saver who wants to use their whole allowance can still do so, by splitting it between a cash ISA and a stocks and shares ISA. The government has also confirmed anti-circumvention rules. Under-65s will not be able to transfer money from a stocks and shares ISA, or an Innovative Finance ISA, back into a cash ISA.

From 6 April 2027 the cash ISA allowance for under-65s drops to £12,000, while the overall £20,000 ISA limit stays the same.

Why the 2026/27 year matters

The timing of the change is what makes this tax year so significant for savers. The 2026/27 tax year, which began on 6 April 2026, is the last full year that under-65s can pour the entire £20,000 into a cash ISA. Once April 2027 arrives, the cash portion of new contributions is capped at £12,000. For anyone sitting on a large cash balance, this is effectively a use-it-or-lose-it moment.

Savers appear to be responding to the deadline in large numbers already. In April 2026 alone, an enormous £12 billion was paid into ISAs across the country. That surge suggests many people are keen to make the most of the generous cash allowance while it lasts. It is a clear sign that the coming change is firmly on the radar of British households.

The wider savings picture

The ISA shake-up is landing at an interesting moment for the broader savings market. The Bank of England held its base rate at 3.75 per cent at its meeting on 30 July 2026, having gradually cut it from a peak of 5.25 per cent. The next interest rate decision is scheduled for 17 September 2026. Some analysts believe borrowing costs could even edge higher again if inflation picks up.

For savers, there is still plenty of competition on the high street. Product choice recently reached a record high, with thousands of savings deals available and hundreds of cash ISA options among them. Average returns have improved too, though experts warn that rates may fade from their recent peaks. Inflation, which cooled to around 2.6 per cent in June 2026, is widely expected to rise again over the coming months.

What to think about now

If you are under 65 and hold a significant amount in cash, this tax year is worth a careful look. Filling a cash ISA up to the full £20,000 now, if it suits your circumstances, locks that money into the tax-free wrapper before the cap arrives. For the longer term, it may be worth understanding how a stocks and shares ISA works, since that is where the rest of the allowance is designed to go.

None of this is a recommendation, and everyone's situation is different. Cash tends to suit short-term goals and money you cannot afford to risk, while investing suits longer time horizons where you can ride out the ups and downs. The key point is simply that a well-known savings rule is about to change. Knowing the deadline gives you time to plan calmly, rather than scrambling at the last minute in early 2027.