The UK ISA allowance in 2026/27: still £20,000, with a change coming next year

The ISA allowance for the 2026/27 tax year is £20,000 — exactly where it has sat since the 2017/18 tax year, making this the ninth year running with no change to the headline figure. The Lifetime ISA and Junior ISA sub-limits are also unchanged. The one genuine piece of news is not about 2026/27 at all: HM Treasury has already confirmed a cut to the cash ISA allowance specifically, for savers under 65, starting the following tax year. Here is exactly how the current allowance is structured, and what changes next.

The 2026/27 allowance, in full

Every adult UK resident gets a £20,000 ISA allowance each tax year, which can be split across cash, stocks and shares, and innovative finance ISAs in any combination, plus a Lifetime ISA sub-limit inside that same £20,000. It resets every 6 April and cannot be carried forward — unused allowance from 2025/26 was simply lost when the new tax year began.

These figures are confirmed directly on GOV.UK's Individual Savings Accounts guidance, which states plainly that the 2026/27 limit is £20,000, and on the dedicated Lifetime ISA and Junior ISA guidance pages for their respective sub-limits.

Why the number looks the same as last year — and the year before that

£20,000 is not a fresh decision for 2026/27; it is the same figure carried forward without a single change since the 2017/18 tax year. Unlike a tax band or a state pension amount, the ISA allowance is not indexed to inflation by any automatic formula — it stays wherever it was last set until a Chancellor deliberately moves it in a Budget. Nine years of an unmoved cash figure means the real spending power of a maxed-out ISA allowance has fallen every one of those years, even though the number on the page has not. None of that changes what £20,000 means for tax purposes today, but it is worth knowing the figure is a policy choice being held steady, not a number recalculated fresh each spring.

The Lifetime ISA: a £4,000 slice with its own bonus

Anyone aged 18 to 39 can open a Lifetime ISA, and anyone with one already open can keep contributing up to age 50. The 2026/27 contribution limit is £4,000, and every pound paid in gets a 25% government bonus on top — up to £1,000 a year on the maximum contribution — provided the money is eventually used to buy a first home worth up to £450,000, or withdrawn from age 60 onward. The £4,000 is not an allowance on top of the standard £20,000; it is a slice inside it, so a saver who puts the full £4,000 into a Lifetime ISA has £16,000 of ISA allowance left for other ISA types in the same tax year.

The Junior ISA: a separate £9,000, not a smaller version of the adult allowance

A Junior ISA has its own £9,000 annual limit for 2026/27, and it is entirely independent of a parent's or guardian's own £20,000 allowance — funding a child's Junior ISA to the full £9,000 does not use up any of an adult's personal allowance, and vice versa. A family with one adult and one child could, in principle, shelter £29,000 across both accounts in the same tax year. Junior ISA funds belong to the child from the moment they are paid in, cannot be withdrawn by a parent for their own use, and convert automatically into an adult ISA when the child turns 18.

What a maxed-out allowance is worth, left to grow

ISA growth is entirely free of both income tax and capital gains tax, which is what makes the allowance worth using rather than just a place to hold cash. Take a saver who pays a one-off £20,000 into a stocks and shares ISA and leaves it invested for 20 years at an assumed 5% average annual return:

None of that £33,066 in growth is taxed on the way out; in an ordinary savings or investment account it would be exposed to capital gains tax above the (much smaller) annual exempt amount, and any interest or dividends along the way would be exposed to income tax once other allowances were used up. The compound interest calculator and the future value calculator run this same arithmetic against your own contribution pattern and assumed return, rather than the flat 5% used here for illustration.

The change that is coming, just not yet

Nothing above changes for 2026/27. But at the Autumn Budget 2025, the Chancellor confirmed that from 6 April 2027 — the start of the following tax year — the amount someone under 65 can pay into a cash ISA specifically will be cut to £12,000, while the overall £20,000 ISA limit stays exactly where it is. In practice that means a saver under 65 from April 2027 can still shelter the full £20,000 across ISA types, but no more than £12,000 of it in cash — the remaining £8,000 would need to go into a stocks and shares or innovative finance ISA to use the full allowance. Savers who are 65 or older at the start of the relevant tax year are exempt from the cut and keep the full £20,000 cash ISA allowance. The GOV.UK factsheet on the 2027 ISA reform sets out the confirmed figures and the age exemption in full. It has no effect on 2026/27 contributions, but it is worth planning around now if cash ISA savings above £12,000 a year are part of a longer-term plan.

Sources

• GOV.UK: Individual Savings Accounts (ISAs)
• GOV.UK: Lifetime ISA
• GOV.UK: Junior Individual Savings Accounts
• GOV.UK: ISA reform 2027 — anti-circumvention rules factsheet

This is general information, not investment or tax advice. Whether an ISA, a pension, or another account is the right home for your savings depends on your own circumstances and goals. For a decision about your own money, speak to a regulated financial adviser or check GOV.UK directly.