See how much your ISA could grow to, completely tax free. Pick a stocks and shares, cash or Lifetime ISA, enter what you save each month, and the calculator applies the 2026/27 allowance, the Lifetime ISA bonus and the full £20,000 cash ISA allowance.
Uses the 2026/27 allowance: £20,000 a year across all your ISAs, £4,000 of it in a Lifetime ISA.
Growth inside an ISA is free of income tax and capital gains tax.
ISA allowance for 2026/27
- Total allowance: £20,000 a year across all your adult ISAs
- Lifetime ISA: up to £4,000 of that, with a 25% government bonus of up to £1,000 a year
- Junior ISA: £9,000 a year per child, on top of your own allowance
- New tax year: the allowance resets on 6 April, and unused allowance does not carry over
The cash ISA cap that was scrapped
The government had planned to cap cash ISAs at £12,000 a year for under-65s from 6 April 2027, but the cut was scrapped in the October 2026 Budget. You can still put the full £20,000 into a cash ISA in 2027/28, and the calculator uses the full allowance. See what changed.
Stocks and shares vs cash ISA
A cash ISA keeps your money safe and pays interest, which suits savings you need within a few years. A stocks and shares ISA invests in funds or shares, so the value goes up and down, but over long periods it has usually grown much faster. Many people keep an emergency fund in cash and invest the rest.
Is a Lifetime ISA worth it?
If you are 18 to 39 and saving for a first home up to £450,000, or for retirement after 60, the 25% bonus is hard to beat. The catch is the 25% charge on other withdrawals, which takes back the bonus and some of your own money. Only use it for money you are sure you will spend on those two goals.
- Live prices and sentiment on every ticker page
- Weekly email with your watchlist movers
- Price alerts on the stocks and coins you follow
Frequently asked questions
Do I pay tax on ISA growth?
No. Interest, dividends and gains inside an ISA are free of UK income tax and capital gains tax, and you do not need to report them.
Can I have more than one ISA?
Yes. You can pay into several ISAs in the same tax year, as long as the total stays within £20,000.
What return should I expect?
Global stock funds have averaged roughly 6% to 8% a year over long periods, with big ups and downs along the way. Cash ISA rates follow the Bank of England base rate.
Not in the UK? Try our Roth IRA calculator for the US or the TFSA calculator for Canada. This calculator gives an estimate for general information only. Not financial advice.
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