ISA Calculator
Project your Stocks & Shares ISA, Cash ISA, or Lifetime ISA with a full year-by-year breakdown. The LISA includes the 25% government bonus on contributions up to £4,000/year, paid until age 50.
Annual ISA allowance: £20,000
Long-run equity average ~7%
Where the final balance comes from
Year-by-year growth
| Year | Contribution | Growth | Balance |
|---|---|---|---|
| Year 1 | £500 | £35 | £535 |
| Year 2 | £500 | £72 | £1,107 |
| Year 3 | £500 | £113 | £1,720 |
| Year 4 | £500 | £155 | £2,375 |
| Year 5 | £500 | £201 | £3,077 |
| Year 6 | £500 | £250 | £3,827 |
| Year 7 | £500 | £303 | £4,630 |
| Year 8 | £500 | £359 | £5,489 |
| Year 9 | £500 | £419 | £6,408 |
| Year 10 | £500 | £484 | £7,392 |
Frequently asked questions
How much can I put in an ISA?
The annual ISA allowance is £20,000 for 2026/27 — you can split this across a Stocks & Shares ISA, Cash ISA, and Innovative Finance ISA in any combination. A Lifetime ISA has a separate £4,000 annual limit (which counts within the £20,000 overall). Contributing £500/year at 7% for 20 years would grow to £21,933.
What is a Lifetime ISA and who should use one?
A Lifetime ISA (LISA) lets you save up to £4,000/year and receive a 25% government bonus — worth up to £1,000/year. You must be aged 18–39 to open one. The money can be used to buy a first home (up to £450,000) or taken as retirement income from age 60. Withdrawals for other purposes incur a 25% charge — which claws back the entire bonus plus ~6.25% of your own contributions. It's most valuable as a first-time buyer savings vehicle.
Are ISA returns tax-free?
Yes — interest, dividends, and capital gains inside an ISA are completely free from UK income tax and capital gains tax, and do not need to be declared on a self-assessment return. This makes them particularly valuable for higher-rate taxpayers who would otherwise pay 40% on savings interest or 24% on investment gains.
Stocks & Shares ISA vs Cash ISA — which is better?
For long investment horizons (10+ years), a Stocks & Shares ISA has historically produced significantly higher returns than cash savings — the long-run FTSE All-Share real return is approximately 5–7% per year. Cash ISAs make more sense for short-term savings or if you need certainty of the nominal amount. In either case, the tax-free wrapper is valuable: use your ISA allowance before taxable accounts.