ISA stands for Individual Savings Account. The main difference between an ISA and other savings accounts is it offers tax-free interest payments. The ISA allowance for the 2024/25 tax year is £20,000. You can have a cash ISA - including a Help to Buy ISA - a stocks and shares ISA, an innovative finance ISA, a Lifetime ISA or a mixture of them all. You must save or invest by April 5 - the end of the tax year.