The ISA allowance is the annual limit on how much you can subscribe to ISAs in a tax year. For 2026/27, the ISA allowance is £20,000.
ISA allowance in plain English
The ISA allowance tells you how much new money you can put into ISAs during a UK tax year. The tax year runs from 6 April to 5 April. For the 2026/27 tax year, the maximum you can save into ISAs is £20,000.
You do not have to put the full amount into one ISA. You can split the allowance across different adult ISA types, such as a Cash ISA, Stocks and Shares ISA, Innovative Finance ISA and Lifetime ISA. The total subscribed across them must stay within the annual limit.
The point of using an ISA is tax sheltering. Interest, dividends and capital gains inside an ISA are normally free from UK tax. That can be useful for cash savers, investors and anyone building long-term wealth.
Unused ISA allowance normally does not carry forward. If you only use £5,000 of the £20,000 allowance, the unused £15,000 is not added to next year’s allowance. This is why many people plan ISA contributions monthly or before the end of the tax year.
The ISA allowance is different from the Personal Savings Allowance, Dividend Allowance and Capital Gains Tax annual exempt amount. Those allowances mostly matter outside ISAs. Inside an ISA, the tax wrapper is doing the work.
Calculate your ISA allowance and growth
Use the ISA calculator to estimate how much allowance you have left, what regular contributions could build to, and how different growth or interest assumptions change the final value.
ISA Calculator
Check remaining allowance, monthly contributions and projected ISA value.
ISA allowance examples
| Example | Amount subscribed | Allowance left |
|---|---|---|
| You pay £5,000 into a Cash ISA | £5,000 | £15,000 |
| You pay £10,000 into a Stocks and Shares ISA | £10,000 | £10,000 |
| You pay £4,000 into a Lifetime ISA and £8,000 into a Stocks and Shares ISA | £12,000 | £8,000 |
| You pay £20,000 across adult ISAs | £20,000 | £0 |
Common ISA allowance mistakes
- Confusing balance with allowance: the allowance limits new money paid in, not the total ISA balance.
- Forgetting the tax year deadline: unused allowance normally disappears after 5 April.
- Ignoring Lifetime ISA limits: the Lifetime ISA has its own £4,000 limit that counts towards the overall ISA allowance.
- Withdrawing from a non-flexible ISA: replacing withdrawn money may still count as a new subscription if the ISA is not flexible.
- Not checking transfer rules: moving ISA money should usually be done through the provider’s ISA transfer process.