A tax-free way to save or invest in the UK, with several types available including Cash ISAs, Stocks and Shares ISAs, Innovative Finance ISAs, and Lifetime ISAs. Any growth or income within an ISA is free from income tax and capital gains tax, up to an annual allowance (£20,000 for the 2026/27 tax year) that can be split across the different types. From 6 April 2027, the Cash ISA allowance for under-65s will fall from £20,000 to £12,000 a year, and interest earned on cash held within a Stocks and Shares ISA will be taxed at 22%.