The ISA allowance is not being cut. That is the first thing to get straight, because it is what most of the headlines imply and it is not what happened.
The overall limit stays at £20,000, and HM Treasury's own factsheet keeps it there. What changes, from 6 April 2027, is how much of that £20,000 a person under 65 may put into cash — and what happens if they try to hold cash somewhere else instead.
The new shape of the allowance
| Under 65 | 65 and over | |
|---|---|---|
| Cash ISA limit | £12,000 | £20,000 |
| Overall ISA limit | £20,000 | £20,000 |
| Starts | 6 April 2027 | 6 April 2027 |
So an under-65 saver with £20,000 to shelter can still shelter all of it. Up to £12,000 of it can sit in cash (opens in a new tab); the remaining £8,000 has to go somewhere that is not a cash ISA.
The intent is not disguised. The reduced cash limit exists to push part of the allowance towards investment rather than deposits. Whether that suits any particular person is a separate question, and it is the one this article is actually about.
The age line is the unusual part
Reducing an allowance is ordinary. Reducing it for one age group and not another is not, and it is the detail worth planning around.
On HM Treasury's figures, at 65 the full £20,000 cash allowance returns. There is no requirement to invest anything, and the overall ceiling is the same £20,000 it was before.
That produces a real and slightly odd effect at the boundary: a saver at 64 has a £12,000 cash limit and a saver at 65 has a £20,000 one, with identical circumstances otherwise. If you are close to that line, the year in which you use a large cash subscription is now a decision rather than a formality.
The three rules that close the obvious workarounds
This is the part that has had the least coverage and will cause the most surprise, because the natural reaction to a cash limit is to look for somewhere else to keep cash inside the wrapper. HM Treasury published three rules (opens in a new tab) that anticipate exactly that.
A 22% charge on interest in a non-cash ISA. A flat-rate charge of 22% will apply to any interest or alternative finance return paid on cash held within a non-cash ISA. So money parked in the cash account of a stocks and shares ISA no longer earns its interest tax-free.
Cash-like assets only as part of the mix. Cash-like assets remain eligible for non-cash ISAs, but only as partial allocations — they cannot make up 100% of the investments. A stocks and shares ISA filled entirely with money market instruments is not a route around the limit.
No transfers back into cash. On HM Treasury's wording, transfers from non-cash ISAs into cash ISAs will not be permitted. Once the money is on the investment side of the wrapper, it does not come back to the cash side.
Read together, these are not incidental anti-abuse provisions. They are the policy. The cash limit alone would have been trivially avoidable, and it is these three rules that make it bite.
What this actually costs, and for whom
Worth being proportionate. Most ISA savers do not use the full £20,000 allowance (opens in a new tab) in a year, and for them nothing changes at all: a £12,000 cash limit is not a constraint on a £4,000 subscription.
It matters to a specific group — people who use most or all of the allowance, and who want it in cash. That includes some very reasonable positions:
- Someone saving a house deposit over two or three years, for whom investment risk is genuinely inappropriate.
- Someone holding an emergency fund large enough to matter.
- Someone who has decided, having thought about it, that they do not want investment risk.
For those savers the £8,000 above the cash limit has to be either invested, or held outside an ISA where interest is taxable beyond the Personal Savings Allowance (opens in a new tab).
That is the honest trade-off, and it is a trade-off rather than a disaster. It is also not a reason to take investment risk you do not want. Tax treatment is a reason to prefer one wrapper over another; it is not a reason to change what you are holding.
You have a full year
The change starts on 6 April 2027. The current tax year runs on the existing rules, and so does the whole of the next one.
That is enough time to do something deliberate rather than rushed. The sensible uses of it are unglamorous: work out whether you actually subscribe near the limit, decide whether the cash you hold is there for a reason or by default, and if you are approaching 65, look at where the age line falls relative to your plans.
The limits for stocks and shares ISAs, and for the other ISA types, are unchanged by this measure.
One further point for anyone near retirement, since the age line falls close to it: the full new State Pension is now £22 below the frozen Personal Allowance, so interest earned outside an ISA lands on top of a tax-free band with almost nothing left in it. And where the money is destined to be inherited rather than spent, pensions come into the inheritance tax net on 6 April 2027 — the same month these ISA rules begin.
What to actually check
- How much do you actually put in each year? Below £12,000 and this changes nothing for you.
- Will you be 65 or over in the 2027 to 2028 tax year? If so, your cash limit is unchanged.
- What is your cash for? A deposit in two years and a long-term pot are different answers.
- Where does your ISA's cash balance sit? Inside a stocks and shares ISA, its interest now carries a 22% charge.
- What is your Personal Savings Allowance? Cash held outside an ISA is not automatically taxed, and for many savers it is not taxed at all.
This article describes the ISA changes as published by HM Treasury and is general information for a United Kingdom audience. It is not investment, tax or financial advice, and it is not a recommendation to hold cash, to invest, or to use any particular product. Rules can change before they take effect. Confirm the position on GOV.UK and take advice from a qualified adviser before acting.
Sources
- GOV.UK — ISA reform 2027: anti-circumvention rules factsheet (opens in a new tab)
- GOV.UK — Individual Savings Accounts (ISAs) (opens in a new tab)
- GOV.UK — Budget 2025: overview of tax legislation and rates (opens in a new tab)
- GOV.UK — Annex A: rates and allowances (opens in a new tab)
- GOV.UK — Income Tax rates and Personal Allowances (opens in a new tab)
This article is general information for a United Kingdom audience and reflects the ISA reform published by HM Treasury at the date of review. It is not investment, tax or financial advice. Announced measures can be amended before they take effect, limits are reviewed, and what suits any individual depends on their circumstances and their attitude to risk. Confirm the current position on GOV.UK and take advice from a qualified adviser before relying on any of this. Last reviewed 16 September 2026.
