The ISA allowance for the 2026/27 tax year (6 April 2026 to 5 April 2027) is £20,000. That is the total you can pay into all your adult ISAs combined, in any mix of cash, stocks and shares, innovative finance and Lifetime ISAs. Within it, no more than £4,000 can go into a Lifetime ISA. Junior ISAs have a separate limit of £9,000 per child. The allowance cannot be carried forward: anything unused on 5 April is lost. From 6 April 2027 a new cap of £12,000 applies to cash ISAs for anyone aged 64 or under at the end of the tax year. The overall £20,000 limit stays the same.
Where the £20,000 comes from
The limit is set by regulation 4ZA(1) of the Individual Savings Account Regulations 1998. It defines the "overall subscription limit" as the total of your subscriptions in a year to all accounts that are not Junior ISAs, and fixes it at £20,000. The same regulation sets the Lifetime ISA limit at £4,000. The figure has been £20,000 since 6 April 2017. In practice:
- It is a limit on payments in, not on balances. Growth, interest and dividends inside an ISA do not use any allowance, so a pot can grow well beyond £20,000;
- It is per person. ISAs cannot be held jointly, so a couple has two separate £20,000 allowances;
- It covers all your ISAs together. Since 6 April 2024 you can pay into more than one ISA of the same type in a year, for example two cash ISAs, as long as the total stays within £20,000;
- Transfers do not count. Moving existing ISA money between providers through a proper transfer is not a new subscription.
How you can split it
You can put the whole £20,000 in one account or spread it across several. These splits all work for 2026/27:
| Cash ISA | Stocks and shares ISA | Innovative finance ISA | Lifetime ISA | Total |
|---|---|---|---|---|
| £20,000 | £0 | £0 | £0 | £20,000 |
| £15,000 | £2,000 | £3,000 | £0 | £20,000 |
| £11,000 | £2,000 | £3,000 | £4,000 | £20,000 |
| £13,000 (two accounts) | £7,000 | £0 | £0 | £20,000 |
A Lifetime ISA attracts a government bonus of 25% of what you pay in, up to £1,000 a year. You can open one only between 18 and 39, and you can pay in until you reach 50.
The April 2027 cash ISA cap
The Individual Savings Account (Amendment) (No. 2) Regulations 2026 (SI 2026/1018) were made on 10 September 2026 and come into force on 6 April 2027. They add a new limit: in any year in which you are 64 or under at the end of that year, your total subscriptions to cash ISAs cannot exceed £12,000. The other £8,000 of the allowance remains available for stocks and shares, innovative finance or Lifetime ISAs.
The age test is applied on 5 April, the last day of the tax year. Someone who turns 65 on any day up to and including 5 April 2028 is 65 at the end of 2027/28, so they can put the full £20,000 into cash ISAs in that year. The same instrument stops under-65s from getting round the cap by subscribing to a stocks and shares ISA and transferring the money to cash. It also ends the tax exemption for interest on cash held inside a stocks and shares or innovative finance ISA: from 2027/28 the provider must pay HMRC a flat-rate charge on that interest at the savings basic rate, which section 5 of the Finance Act 2026 sets at 22% for 2027/28. In 2026/27 that interest is still tax-free.
None of this applies yet. For the rest of 2026/27 the only limits are the £20,000 overall and £4,000 Lifetime ISA limits, and transfers from stocks and shares to cash are still allowed. The practical point: if you are under 65 and keep most of your savings in cash, this is the last tax year in which you can put the full £20,000 into a cash ISA. Money already in a cash ISA is not affected by the cap. The cap limits only new subscriptions.
Flexible ISAs: withdrawing and replacing
Normally, money you take out of an ISA does not restore your allowance. A flexible ISA is different: if the provider's terms allow it, you can withdraw cash and replace it in the same tax year without using up more allowance.
Example (from HMRC's guidance): you pay £10,000 into an ISA in 2026/27 and later withdraw £3,000. If the ISA is flexible, you can still pay in £13,000 that year: the £10,000 unused allowance plus the £3,000 replacement. If it is not flexible, you can pay in only £10,000.
Two limits apply. A replacement of money you paid in during earlier years must go back into the same account. From April 2027, replacements that count as current-year subscriptions are also subject to the £12,000 cash cap. Lifetime ISAs and Junior ISAs cannot be flexible.
Extra allowance for a surviving spouse
When an ISA holder dies, their spouse or civil partner can claim an additional permitted subscription on top of their own £20,000. It equals the value of the deceased's ISAs, measured either at the date of death or when the account stops being a "continuing account of a deceased investor". The couple must have been living together at the date of death, and the surviving partner does not need to have inherited the ISA assets to claim. The tax treatment of the ISA itself on death is covered in our guide to whether ISAs are subject to inheritance tax.
What happens if you pay in too much
Subscriptions over the limit make the account invalid. Under regulation 4A, an account that is invalid only because the overall limit was exceeded can be repaired. An HMRC officer issues a "notice of discovery", the valid part keeps its tax exemption, and the provider must follow any direction to remove the excess subscriptions, and the investments and income representing them, within 30 days. The amount removed loses ISA protection. Keep your own running total across all providers. Each provider sees only its own account, so an overpayment split across several ISAs often goes unnoticed until HMRC compares the returns.
Using the allowance well
- Fund a spouse's ISA. Gifts between spouses are generally free of inheritance tax, and the other partner's £20,000 doubles the household shelter;
- Bed and ISA. Selling shares held outside an ISA and buying them back inside one uses the allowance and can use your capital gains tax exemption at the same time. See our guide to bed and ISA and bed and spouse;
- Review cash plans before April 2027. If you are under 65, decide this year whether a full £20,000 cash subscription is worth making.
Primary sources: the ISA Regulations 1998, regulation 4ZA; SI 2026/1018; HMRC's guidance on Individual Savings Accounts and additional permitted subscriptions. For how ISA interest fits alongside other tax-free savings income, see our guide to the personal savings allowance.
ISAs are one part of a household's savings and investment plan. Acumon's private client tax team can review how your ISA, pension and taxable holdings fit together as part of wider tax planning.