ISA Calculator
🏠 Free ToolSimulate your ISA growth over time with annual contributions up to £20,000. See projected value, total contributions, and tax-free growth with a visual chart.
How it Works
Individual Savings Accounts (ISAs) are one of the most powerful tax-efficient savings tools available to UK residents. With an annual contribution limit of £20,000, all growth within an ISA — whether from interest, dividends, or capital gains — is completely free from UK tax. This makes ISAs essential for long-term wealth building.
The power of ISAs becomes most apparent over longer time horizons thanks to compound growth. A consistent annual contribution of £10,000 into a Stocks & Shares ISA returning 7% per year would grow to over £400,000 in 20 years, with nearly £200,000 of that being tax-free growth. Without the ISA wrapper, capital gains tax and dividend tax would significantly reduce these returns.
There are several types of ISA available: Cash ISAs for low-risk savings, Stocks & Shares ISAs for investment growth, Innovative Finance ISAs for peer-to-peer lending, and Lifetime ISAs (with a £4,000 sub-limit) for first-time home purchases or retirement. The £20,000 allowance is shared across all types.
Use this calculator to project how your ISA could grow over time based on your planned contributions, investment period, and expected return. Adjust the parameters to see how even small changes in contribution amount or investment horizon can dramatically affect your final balance.
Frequently Asked Questions
What is the ISA annual allowance?
The ISA annual allowance is £20,000 for the 2024/25 tax year. This is the maximum you can contribute across all ISA types (Cash ISA, Stocks & Shares ISA, Innovative Finance ISA, Lifetime ISA) in a single tax year.
What makes ISAs tax-free?
All income and capital gains within an ISA are completely tax-free. You pay no income tax on interest or dividends, and no capital gains tax when you sell investments at a profit. This makes ISAs one of the most tax-efficient savings vehicles in the UK.
What return should I assume for a Stocks & Shares ISA?
Historical UK stock market returns have averaged around 7-8% per year before inflation (4-5% after inflation). However, past performance does not guarantee future results. A conservative assumption might be 5-6% for long-term planning.
Can I withdraw from my ISA?
Yes, you can withdraw from your ISA at any time. With a Flexible ISA, you can replace withdrawn funds within the same tax year without it counting towards your annual allowance. Non-flexible ISAs count withdrawals as used allowance.
What is the difference between a Cash ISA and Stocks & Shares ISA?
A Cash ISA holds cash deposits and earns interest like a savings account. A Stocks & Shares ISA holds investments such as shares, bonds, and funds. Over long periods, Stocks & Shares ISAs have historically provided higher returns but carry investment risk.