● 2026/27 · £20,000 allowance · Tax-free

ISA Savings Calculator

Q: How much can I put in an ISA in 2026/27?

The annual ISA allowance for 2026/27 is £20,000. You can split it across a cash ISA, a stocks and shares ISA, an innovative finance ISA and a Lifetime ISA (up to £4,000 of the £20,000), but the total cannot exceed £20,000.

Q: How much could £500 a month grow to in an ISA?

Paying £500 a month into an ISA earning 5% a year could grow to about £77,641 after 10 years. Of that, £60,000 is your own contributions and roughly £17,641 is tax-free investment growth.

Q: Do I pay tax on ISA interest or gains?

No. Interest, dividends and capital gains earned inside an ISA are completely tax-free, and you do not need to declare them on a tax return. That tax shelter is the main advantage of an ISA over an ordinary savings or investment account.

Save £500 a month into an ISA growing at 5% a year and after 10 years you could have about £77,641 — of which roughly £17,641 is completely tax-free growth on top of your £60,000 of contributions. Enter your own plan below.

📈 Tax-free compound growth 🛡️ £20,000 allowance 🏛️ GOV.UK ISA rules

Project your ISA pot

United Kingdom · 2026/27 · tax-free

Monthly contribution

Expected annual growth

Years

ISA allowances for 2026/27

An ISA (Individual Savings Account) lets your savings and investments grow free of UK tax. Each tax year you have an allowance you can split across different ISA types, and any unused allowance does not carry over.

ISA type	2026/27 limit	Notes
Overall ISA allowance	£20,000	Across all adult ISAs combined
Lifetime ISA (LISA)	£4,000	Part of the £20,000; 25% government bonus
Junior ISA (JISA)	£9,000	Separate allowance, for under-18s
Tax on ISA returns	0%	Interest, dividends and gains are tax-free

The £20,000 limit in monthly terms. £20,000 a year is £1,666.67 a month. The default £500 a month sits comfortably inside the allowance, leaving room for a lump sum or a stocks-and-shares top-up later in the year.

A worked example: £500 a month at 5%

The calculator uses the future-value of a regular monthly investment. For £500 a month at 5% over 10 years:

Monthly growth rate: 5% ÷ 12 = 0.4167%.
Number of payments: 10 × 12 = 120.
Total contributed: £500 × 120 = £60,000.
Projected pot: about £77,641.
Tax-free growth: £77,641 − £60,000 = roughly £17,641.

Because every penny of that growth is sheltered inside the ISA, you keep all of it — there is no Income Tax, Dividend Tax or Capital Gains Tax to pay.

Getting the most from your ISA

A few habits make a big difference to the final pot:

Start early — compounding rewards time more than the amount you save.
Use the full allowance if you can — unused allowance is lost at the end of the tax year.
Reinvest growth — leaving returns inside the ISA keeps the tax-free compounding going.

ISA FAQs

How much can I put in an ISA in 2026/27?

The annual ISA allowance is £20,000. You can spread it across a cash ISA, stocks and shares ISA, innovative finance ISA and a Lifetime ISA (up to £4,000 of the £20,000), but the total cannot exceed £20,000.

How much could £500 a month grow to in an ISA?

About £77,641 over 10 years at 5% annual growth — £60,000 from your contributions and roughly £17,641 of tax-free growth.

Do I pay tax on ISA interest or gains?

No — interest, dividends and capital gains inside an ISA are tax-free and do not go on a tax return. See GOV.UK.

Total contributed	£0
Tax-free growth	£0
Projected pot	£0