Your ISA Allowance Is Use It or Lose It. Here Is What to Check Now.

You are 41. The mortgage, childcare and pension all get paid first. Your ISA is somewhere lower down the list. If you have not used much of this year's allowance, you are normal. You also have a deadline: 5 April 2027.

The 2026/27 allowance is £20,000 across your adult ISAs. Up to £4,000 of that can go into a Lifetime ISA if you are eligible. The allowance cannot be carried forward. Whatever is unused when the tax year ends disappears.

Most ISA savers do not use the full £20,000

HMRC's latest annual savings statistics show that 22.7% of ISA subscribers used the maximum allowance in 2022/23. The biggest group, 41.9%, contributed between £1 and £2,499. In other words, more than three in four ISA subscribers did not use the full allowance.

That benchmark matters. Not maxing an ISA does not mean you are bad with money. It means you are in the majority. But normal and best for your future are not always the same thing. The useful question is not whether you can find £20,000. It is how much of the allowance you can use without weakening your emergency fund or creating expensive debt.

Source: HMRC Annual Savings Statistics, September 2025. Subscription-size data is for 2022/23, the latest year in the publication with this breakdown.

What just happened

The 2025/26 ISA allowance closed on 5 April 2026. If you had unused 2025/26 allowance, that allowance is gone. It cannot be carried forward. It cannot be added to the 2026/27 allowance. It is gone for good. The full explanation of how the allowance works is on the how ISAs work page.

The 2026/27 ISA allowance opened on 6 April 2026 with a fresh £20,000. It will close on 5 April 2027. Whatever you do not put into an ISA between those two dates is also gone. The pattern is the same every year. The reset is a hard deadline, not a soft one.

What most readers do instead

Most readers do not use the full allowance. The pattern is familiar: open a cash ISA with the first £1,000 that comes along in April or May, then leave the rest unspent because the rest feels like too much to think about. By August, the £1,000 is sitting there. The other £19,000 is sitting in a current account or a low-interest savings account, earning below CPI at standard variable rates but competitive with CPI at the top of the market.

The reasons are practical, not personal. Most adults in this age band are paying off a mortgage, raising children, supporting ageing parents, or all three at the same time. The ISA allowance is real money but it does not feel like the most urgent bill. The reader who has not used it is not failing. They are doing what most people actually do. The default is partial use, not full use.

What one unused year can cost over 20 years

Imagine you have £5,000 available for long-term investing but leave it outside an ISA and never invest it. At 5% annual growth, £5,000 could become about £13,266 after 20 years. That is £8,266 of potential growth you chose not to pursue. Investment returns are not guaranteed, and the value can fall, but doing nothing has an outcome too.

Missing the full £20,000 allowance once is a larger example. At the same illustrative 5% annual growth rate, £20,000 could become about £53,066 after 20 years. This is not a reason to empty your emergency fund. It is a reason to stop treating an unused allowance as a neutral decision.

The £400-a-month option

The single most useful thing the unspent reader can do is set up a monthly standing order from this month. £400 a month into a stocks and shares ISA from August 2026 to April 2027 is £3,200 used of the £20,000 allowance and a position that is already working.

If the standing order is then left in place through 2027 and beyond, the position becomes the basis of a much longer trajectory. £400 a month from 35 to 55 at a 5% annual growth rate, charges excluded, lands around £164,000. The same £400 a month starting ten years later from 45 to 55 lands around £62,000. The difference is roughly £102,000. The maths is the maths. The years are the years.

Worked from 6 April 2026 (start of tax year) to 5 April 2027 (end). The £1,667 plan uses 12 monthly payments to reach £20,000 by 5 April 2027. The £2,500 plan uses 8 monthly payments from August to March to reach £20,000. Either plan works. The point is to set up something that runs automatically.

The lump-sum option

If you have £5,000 to £10,000 sitting in a current account, the maths favours moving it into an ISA wrapper this month rather than waiting until March. The reasons are not just about using the allowance. They are about the wrapper itself. Cash inside an ISA wrapper pays no tax on the interest. Cash outside one does. The wrapper is the value.

Whether that chunk goes into a cash ISA or a stocks and shares ISA is a separate decision. The cash ISA is right for the chunk you might need within five years. The stocks and shares ISA is right for the chunk you will not need for ten years plus. The cash vs investment calculator shows where your £20k should go using the 28 July 2026 rates snapshot. Run it before deciding what to move this month.

The deadline reality

There are eight months left in the 2026/27 tax year. Whatever the reader does with the £20,000 allowance, the clock runs out on 5 April 2027. The two routes above (monthly standing order and lump sum) both use the allowance in full by that date. A third route is to do nothing and lose the unspent part. The default is the third route. Most readers end up there not by decision but by drift.

The thing the reset month changes is the drift. It puts a date on the calendar and a number against the allowance. The decision does not have to be the full £20,000. It can be £100 this month and a monthly standing order for the rest. It can be one ISA opened and left alone. The point is not the size. The point is that something runs.

What to do this month

One specific action, ordered by how much it moves the dial. Any of them is a genuine step forward. None of them requires having used your ISA before.

For the cash vs stocks and shares decision that determines what goes inside the wrapper, see the cash ISA vs stocks and shares ISA page. For the broader context of how ISAs fit alongside pensions and the State Pension forecast, see the ISA vs SIPP order of operations page. For the May reset-moment explanation of what the allowance is, see the ISA allowance just reset post.

For the wider four-indicator picture of whether you are on track financially at all, see am I on track financially and the average UK savings by age benchmarks.