ISAs explained: a plain-English guide for UK savers and investors

An Individual Savings Account (ISA) lets UK residents save or invest without paying income tax, dividend tax or capital gains tax on the returns. Because the wrapper is free to use, it is one of the simplest ways to keep more of your money working for you.

The main types of ISA

• Cash ISA – works like a savings account, with interest paid tax-free.
• Stocks and shares ISA – lets you invest in funds, shares and other investments. Your capital is at risk, and the value can fall as well as rise.
• Lifetime ISA – for adults under 40 at opening, designed for a first home or retirement, with a government bonus on contributions. Withdrawals for other reasons can incur a penalty.
• Innovative Finance ISA – holds peer-to-peer and similar loans. It carries higher risk and is not covered in the same way as a bank deposit.

The annual allowance

Every tax year runs from 6 April to 5 April, and each adult has an overall ISA allowance for that period. You can split it across different ISA types, but you cannot exceed the total. Unused allowance does not carry forward, so it is worth checking what applies to the current tax year on gov.uk before you pay in.

Things to check before you open one

1. Charges – platform and fund fees compound over time, so compare them carefully.
2. Access – some cash ISAs restrict withdrawals; ask whether you can take money out and put it back without losing allowance (a "flexible" ISA).
3. Protection – cash held with UK-authorised banks and building societies is covered by the Financial Services Compensation Scheme up to the current limit; investments are protected differently.
4. Transfers – if you move an ISA, use the official transfer process rather than withdrawing the cash, otherwise the tax-free status is lost.

Who benefits most?

Basic-rate taxpayers with a Personal Savings Allowance may not owe tax on modest savings interest anyway, but an ISA gives certainty if your balances or rates rise. For investors, the shelter from dividend tax and capital gains tax becomes more valuable as portfolios grow.

This article is general information, not personal financial advice. Rules and allowances change, so always check the latest position on gov.uk or with a regulated adviser.