ISA Calculator UK 2025/26
Updated: April 2025 for 2025/26 | Data sources: HMRC, FCA
Project your ISA pot with the full £20,000 allowance. Compare cash vs stocks and shares growth.
ISA Allowances and Rules 2025/26
An ISA (Individual Savings Account) lets you save or invest up to £20,000 per year completely free of income tax and Capital Gains Tax. You can split this allowance between a Cash ISA and a Stocks and Shares ISA in any combination, as long as the total does not exceed £20,000.
Cash ISA vs Stocks and Shares ISA
A Cash ISA works like a savings account — your money earns interest risk-free. The best Cash ISA rates in 2025 are around 4.5-5% AER. A Stocks and Shares ISA invests in the stock market, offering potential for higher returns (historically around 7% per year for a global index fund) but with the risk your money could fall in value.
Lifetime ISA (LISA)
The Lifetime ISA has a separate £4,000 annual allowance and attracts a 25% government bonus. It can only be used for a first home purchase or retirement. Withdrawing for other reasons incurs a 25% penalty which effectively claws back the bonus plus some of your own money.