Stocks & Shares ISA Calculator
Project tax-free growth inside a Stocks & Shares ISA.
£6,000/yr of £20,000 allowance
All growth and withdrawals from a Stocks & Shares ISA are free of UK income tax and capital gains tax. The annual allowance is £20,000 (2025/26).
About this calculator
A Stocks & Shares ISA lets your investments grow completely free of UK income tax and capital gains tax, with an annual contribution allowance of £20,000 (2025/26). This calculator projects what your ISA could be worth from your current balance plus regular monthly contributions, compounding at your expected rate of return.
Because all growth and withdrawals are tax-free, an ISA is usually the first port of call for UK investors before a general investment account. The tool flags if your monthly amount would breach the annual allowance.
Frequently asked questions
What is the ISA allowance?
For 2025/26 you can pay up to £20,000 across all your ISAs in the tax year. Unused allowance does not carry over to the next year.
Is the growth really tax-free?
Yes. Gains and dividends inside a Stocks & Shares ISA are free of UK capital gains tax and dividend tax, and you don't declare them on a tax return.
Related calculators
These calculators are for general information and planning only. They use the assumptions you enter and do not constitute financial, tax, or investment advice. Tax figures are simplified estimates for the stated tax year. Returns are not guaranteed; verify figures independently before making decisions.