ISA allowance and cash ISA calculator
This ISA allowance calculator shows how much of your £20,000 limit is left for 2026/27, how the cash ISA limit changes from April 2027, and how a cash ISA could grow. Use the cash ISA calculator tab to project interest at the rate you are offered.
Rules last checked 13 October 2026. Limits for 2026/27 and 2027/28.
Tax year
Age
From 6 April 2027 the cash ISA limit depends on whether you are under 65.
ISA allowance left
£20,000.00
You have £20,000.00 of your £20,000 ISA allowance left.
- Total paid in
- £0.00
- Cash ISA room left
- £20,000.00
Show the working
- Total paid in = cash + stocks and shares + innovative finance + Lifetime ISA = £0.00.
- Allowance left = £20,000 − £0.00, not below £0 = £20,000.00.
- Cash ISA limit for 2026/27, under 65: £20,000.00.
- Cash ISA room = lower of (£20,000.00 − cash paid in) and £20,000.00, not below £0 = £20,000.00.
- Lifetime ISA bonus = 25% × lower of Lifetime ISA payments and £4,000 = £0.00.
Nothing you enter leaves your device. General information, not financial or investment advice. ISA rules can change; check GOV.UK before paying in.
ISA allowance 2026/27
Your ISA allowance 2026/27 is £20,000. The tax year runs from 6 April to 5 April, so the 2026/27 allowance must be used by 5 April 2027. You can save in cash ISAs, stocks and shares ISAs, innovative finance ISAs and Lifetime ISAs.
You must be 18 or over to open an ISA. You can put the whole allowance in one account or split it across several, including more than one of the same type. You do not pay tax on interest on cash in an ISA, or on income or gains from investments in an ISA.
Cash ISA limit changes from April 2027
From 6 April 2027 the cash ISA limit is £12,000 a year for people under 65. People aged 65 or over keep a £20,000 cash ISA limit. The overall £20,000 ISA limit stays the same until April 2031.
Under the draft rules, people under 65 will not be able to transfer from stocks and shares or innovative finance ISAs into cash ISAs, and a charge will apply to interest paid on cash held in those ISAs. These rules were still being finalised when this page was last reviewed. Check GOV.UK for the final rules.
| Limit | 2026/27 | 2027/28 |
|---|---|---|
| Overall ISA allowance | £20,000 | £20,000 |
| Cash ISA limit, under 65 | £20,000 | £12,000 |
| Cash ISA limit, 65 or over | £20,000 | £20,000 |
| Lifetime ISA limit | £4,000 | £4,000 |
| Junior ISA limit (per child) | £9,000 | £9,000 |
GOV.UK states the £20,000, Lifetime ISA £4,000 and Junior ISA £9,000 limits stay unchanged until April 2031. The cash ISA change is announced for 6 April 2027.
Lifetime ISA, Junior ISA and the £20,000 limit
Lifetime ISA
You can pay up to £4,000 a year into a Lifetime ISA and the government adds a 25% bonus, up to £1,000 a year. You must make your first payment before you turn 40, and you can pay in until you are 50. Lifetime ISA payments count towards your £20,000 allowance.
| You pay in | Bonus |
|---|---|
| £1,000 | £250 |
| £2,000 | £500 |
| £4,000 | £1,000 |
Junior ISA
The Junior ISA limit is £9,000 a year, for children under 18 living in the UK (there is an exception for children of Crown servants). The child can take control of the account at 16 but cannot withdraw the money until 18.
Cash ISA calculator: project your interest
The cash ISA calculator turns the AER you enter into an equivalent monthly rate, adds interest each month, and assumes your deposits are made at the end of each month. Your starting balance earns interest from the first month.
| Starting balance | 3% AER | 4% AER | 5% AER |
|---|---|---|---|
| £5,000 | £150.00 | £200.00 | £250.00 |
| £10,000 | £300.00 | £400.00 | £500.00 |
| £20,000 | £600.00 | £800.00 | £1,000.00 |
Illustration only. AER is an input, not a forecast.
| Monthly deposit | 1 year | 5 years | 10 years |
|---|---|---|---|
| £250 a month | £3,054.61paid in £3,000 | £16,544.76paid in £15,000 | £36,673.98paid in £30,000 |
| £500 a month | £6,109.22paid in £6,000 | £33,089.51paid in £30,000 | £73,347.96paid in £60,000 |
| £1,000 a monthA monthly deposit above £1,000 exceeds the 2027/28 under-65 cash ISA limit. | £12,218.44paid in £12,000 | £66,179.02paid in £60,000 | £146,695.92paid in £120,000 |
Illustration only. AER is an input, not a forecast.
Transferring an ISA
You can move savings from one ISA provider to another at any time, and the savings can come from this year or earlier years. Restrictions apply to Lifetime ISAs and Junior ISAs, and innovative finance ISAs may not allow non-cash transfers.
If you withdraw money without using a transfer form, you cannot reinvest that part of your allowance. Cash ISA transfers should take no more than 15 working days, and other transfers no more than 30 calendar days.
About this calculator
Last reviewed 13 October 2026. The allowance checker treats the £12,000 cash ISA limit from 6 April 2027 as part of your £20,000, not on top of it. The cash ISA projection uses the AER you enter with end-of-month deposits. It does not show provider rates, give investment advice or model Junior ISAs in the allowance checker. Read how we build and check our calculators.
Frequently asked questions
What is the ISA allowance for 2026/27?
In the 2026 to 2027 tax year the most you can save in ISAs is £20,000. You can put it all in one account or split it across several accounts.
What is the cash ISA limit from April 2027?
From 6 April 2027 the annual cash ISA limit is £12,000 for people under 65. People aged 65 or over can still pay up to £20,000 into cash ISAs. The overall ISA limit stays at £20,000 until April 2031. Check GOV.UK for the final rules, as the regulations were still being finalised when this page was reviewed.
Can I put £20,000 into a cash ISA in 2026/27?
Yes, if you use no other ISA allowance in 2026/27. The £12,000 cash ISA limit for under 65s only starts on 6 April 2027. The tax year ends on 5 April 2027.
Can I pay into more than one ISA?
Yes. You can save up to £20,000 in one account or split the allowance across multiple accounts, including more than one cash ISA. You can pay into only one Lifetime ISA in a tax year.
Does a Lifetime ISA count towards the £20,000 ISA allowance?
Yes. The Lifetime ISA limit of £4,000 a year counts towards your overall annual ISA limit. The government adds a 25% bonus, up to £1,000 a year.
Is the interest in a cash ISA tax-free?
Yes. You do not pay tax on interest on cash in an ISA, or on income or capital gains from investments in an ISA.
What is the Junior ISA limit?
The Junior ISA limit is £9,000 a year. The child must be under 18 and living in the UK. They can take control of the account at 16 but cannot withdraw the money until they turn 18.
How old do I have to be to open an ISA?
You must be 18 or over to open an ISA. To open a Lifetime ISA you must also be under 40, and you can pay into it until you are 50.
Can I transfer my ISA to another provider?
Yes, you can move savings from one provider to another at any time, including savings from earlier years. If you withdraw the money without using a transfer form, you cannot reinvest that part of your tax-free allowance. Cash ISA transfers should take no more than 15 working days.
Is the cash ISA calculator on PayPrompt a forecast of my interest?
No. It uses the AER you enter and assumes deposits at the end of each month. Rates can change, so treat the result as an illustration.
Sources
Checked 13 October 2026:
Browse all UK calculators.
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