How much will your ISA be worth?
Tax-free growth every year. Use your full £20,000 allowance, pick an assumed return, and see how compounding builds wealth over 5, 10, 20 or 30 years — completely free of Income Tax and CGT.
| Year | Contributions | Pot value |
|---|---|---|
| 1 | £10,000 | £10,600 |
| 2 | £20,000 | £21,836 |
| 3 | £30,000 | £33,746 |
| 4 | £40,000 | £46,371 |
| 5 | £50,000 | £59,753 |
| 6 | £60,000 | £73,938 |
| 7 | £70,000 | £88,975 |
| 8 | £80,000 | £104,913 |
| 9 | £90,000 | £121,808 |
| 10 | £100,000 | £139,716 |
| 11 | £110,000 | £158,699 |
| 12 | £120,000 | £178,821 |
| 13 | £130,000 | £200,151 |
| 14 | £140,000 | £222,760 |
| 15 | £150,000 | £246,725 |
| 16 | £160,000 | £272,129 |
| 17 | £170,000 | £299,057 |
| 18 | £180,000 | £327,600 |
| 19 | £190,000 | £357,856 |
| 20 | £200,000 | £389,927 |
Projections are illustrative only. Investment returns are not guaranteed.
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How it works
ISA types and allowances
Total ISA limit: £20,000/year (Cash, Stocks & Shares, Innovative Finance, or Lifetime ISA). Lifetime ISA: max £4,000/year (counts toward the £20k). Junior ISA: £9,000/year (separate allowance).
Tax advantages
All growth, interest and dividends inside an ISA are completely free of Income Tax and Capital Gains Tax — and you never need to declare them on a tax return. The compounding effect over decades is substantial.
Cash vs Stocks & Shares
Cash ISAs offer certainty but currently earn around 4–5%. Stocks & Shares ISAs have historically returned 6–8% per year over long periods, but with volatility. For 5+ year horizons, equities have typically outpaced inflation more reliably.
LISA for first-time buyers
If you're saving for your first home (up to £450,000) or retirement, the Lifetime ISA adds 25% to your contributions (up to £1,000/year bonus). Use the separate LISA calculator for a detailed projection.
ISA allowances reset on 6 April
Unused allowance does NOT carry forward to the next year. If you miss a year, that £20,000 is gone permanently. Consider setting up a standing order to maximise each year.