Savings & ISA
Project how your ISA savings grow with compound returns. Covers Cash ISA, Stocks & Shares ISA, and Lifetime ISA with the 25% government bonus.
Max £20,000 / year across all ISA types
UK market historical average: ~7% p.a. (not guaranteed)
Projected ISA balance after 20 years
£208,316
£120,000 contributions · £88,316 growth
Contributions made at the start of each year, growth applied annually
| Year | Contribution | Growth | Balance |
|---|---|---|---|
| Year 1 | £6,000 | £300 | £6,300 |
| Year 2 | £6,000 | £615 | £12,915 |
| Year 3 | £6,000 | £946 | £19,861 |
| Year 4 | £6,000 | £1,293 | £27,154 |
| Year 5 | £6,000 | £1,658 | £34,811 |
An Individual Savings Account (ISA) is a tax-free wrapper: interest, dividends, and capital gains earned inside an ISA are never subject to UK tax. This calculator shows how much of your £20,000 annual allowance you have used across different ISA types, and projects how your ISA portfolio could grow tax-free over time using compound interest.
The ISA allowance resets each tax year on 6 April and cannot be carried forward. You can split it however you like across a Cash ISA, Stocks and Shares ISA, Innovative Finance ISA, and a Lifetime ISA (up to £4,000 of your allowance). Unused allowance is lost permanently. Even £1 a day unused costs you £365/year of tax-free capacity.
A Cash ISA earns interest tax-free, making it especially valuable for higher and additional-rate taxpayers who have already used their Personal Savings Allowance (£500 for higher rate, £0 for additional rate). A Stocks and Shares ISA invests in funds, shares, or bonds — historically producing higher long-term returns than cash but with more short-term volatility. For money you don't need for 5+ years, a Stocks and Shares ISA typically grows significantly more.
The Lifetime ISA is available to 18–39 year olds and adds a 25% government bonus (up to £1,000/year) on contributions up to £4,000/year. It can only be used to buy a first home (up to £450,000) or from age 60. Withdrawing for any other reason incurs a 25% government penalty which actually returns less than you put in. Use the Lifetime ISA Calculator to compare it with a pension for retirement savings.