Last updated: April 2026 · Sourced from official UK government publications
This is a plain-English definitions guide. All figures and rules are drawn from HMRC and gov.uk official sources. This is not financial advice, see the disclaimer below.
A stocks and shares ISA is a tax-efficient investment account that lets you put up to £20,000 per year into the stock market. Any dividends you receive and any growth in value are completely protected from UK tax, no income tax on dividends, no capital gains tax on gains. Here’s how it works, explained simply.
A stocks and shares ISA is a type of Individual Savings Account that holds investments rather than cash. Where a cash ISA earns interest on money you deposit, a stocks and shares ISA holds assets that can rise or fall in value, such as shares, funds, and investment trusts.
The “ISA wrapper” is what makes it different from a standard investment account. Inside the wrapper, your investments are shielded from UK income tax and capital gains tax. Outside an ISA, dividends above the dividend allowance are taxed, and gains above the annual CGT exempt amount are taxed. Inside an ISA, neither applies, no matter how much your investments grow.
The key differences between a stocks and shares ISA and a cash ISA:
| Stocks & Shares ISA | Cash ISA | |
|---|---|---|
| What it holds | Investments (shares, funds, trusts) | Cash deposits |
| How it grows | Market returns, value can go up or down | Interest at a fixed or variable rate |
| Risk level | Variable, you can lose money | Capital is protected (up to FSCS limits) |
| Tax on returns | No income tax on dividends; no CGT on gains | No income tax on interest |
| Annual allowance | Up to £20,000 (shared across all ISAs) | Up to £20,000 (shared across all ISAs) |
| Best suited for | Long-term goals (typically 5+ years) | Short-term savings and emergency funds |
The £20,000 annual allowance is shared across all your ISAs combined. If you put £8,000 into a cash ISA in a tax year, you can put up to £12,000 into a stocks and shares ISA in the same year, but not a penny more across both.
A stocks and shares ISA can hold shares in listed companies, funds (unit trusts and OEICs), investment trusts, exchange-traded funds (ETFs), and government or corporate bonds. Cryptocurrency, physical gold, and most alternative assets are not permitted under current HMRC rules. The specific investments available depend on your provider.
A stocks and shares ISA can hold a wide range of investments. HMRC sets out the permitted investments, the main categories are:
Not everything is permitted. Cash inside a stocks and shares ISA is generally held only temporarily, for example, between selling one investment and buying another. Cryptocurrency, physical gold, and most alternative assets are not permitted ISA investments under current HMRC rules.
You can contribute up to £20,000 per tax year across all your ISAs combined, this is the annual ISA allowance for 2025/26. The limit is shared across all ISA types you hold. Unused allowance cannot be carried forward; it resets on 6 April each year.
Every UK adult gets a single ISA allowance each tax year: £20,000 in 2025/26. This is a total limit across all the ISAs you hold, cash ISAs, stocks and shares ISAs, innovative finance ISAs, and Lifetime ISAs (up to £4,000 of the allowance). You cannot carry unused allowance forward into the next tax year, use it or lose it.
From April 2024, HMRC changed the rules to allow you to open and contribute to multiple ISAs of the same type in the same tax year (previously you could only open one of each type per year). The £20,000 cap still applies across everything combined.
How the allowance can be split, an example:
| ISA type | Amount contributed this tax year |
|---|---|
| Cash ISA | £5,000 |
| Stocks and shares ISA | £11,000 |
| Lifetime ISA | £4,000 |
| Total | £20,000 (at the limit) |
The allowance resets each tax year on 6 April. There is no minimum amount, you can contribute as little or as much (up to £20,000) as you like.
Withdrawals do not restore your allowance. If you invest £20,000 and then withdraw £5,000, you cannot put that £5,000 back in the same tax year, you have already used your full allowance. Some providers offer “flexible ISAs” that do allow re-depositing of withdrawn funds in the same year, but this is a feature specific to certain accounts and providers, not a standard ISA rule.
Inside a stocks and shares ISA, dividend income is exempt from UK income tax and any investment growth is free from capital gains tax, no matter how large. You do not need to declare ISA income or gains on a Self Assessment tax return. This tax protection applies as long as the money remains inside the ISA wrapper.
The central benefit of a stocks and shares ISA is the tax treatment. Inside the ISA wrapper, two major taxes do not apply:
There is also no need to declare ISA income or gains on your Self Assessment tax return. The ISA wrapper handles the tax treatment automatically.
What the ISA does not shelter you from:
All ISA tax rules are set by HMRC. The current rules are published at gov.uk/individual-savings-accounts.
A cash ISA holds money on deposit and earns interest, your capital is protected. A stocks and shares ISA holds investments such as shares, funds, and bonds, and the value can rise or fall. Both are sheltered from UK income tax and capital gains tax, but a stocks and shares ISA carries investment risk that a cash ISA does not.
Yes. The value of investments inside a stocks and shares ISA can fall as well as rise, and you may get back less than you originally invested. The ISA wrapper provides tax protection but does not protect against investment losses. These accounts are generally considered most appropriate for longer time horizons of five years or more, where there is more opportunity to ride out short-term market falls.
Up to £20,000 per tax year across all your ISAs combined. The £20,000 is the total annual ISA allowance, contributions to other ISA types in the same year reduce what you can add to a stocks and shares ISA. The allowance resets each 6 April and cannot be carried forward if unused.
Yes. You can transfer funds from a cash ISA to a stocks and shares ISA using a formal ISA transfer process, without losing the tax-free status of the money or counting against your current-year allowance. Simply withdrawing the money and redepositing it would use up your annual allowance, so always use a formal transfer. Contact your receiving provider to start the process.
HMRC permits a wide range of investments including shares in listed companies, unit trusts and open-ended investment companies (OEICs), investment trusts, exchange-traded funds (ETFs), and government and corporate bonds. Cryptocurrency, physical gold, and most alternative assets are not permitted under current HMRC rules. The specific investments available will depend on the provider you choose.
Join FinanceSimply’s weekly newsletter for plain-English guides to UK personal finance, no jargon, no product pitches.
Subscribe free →Not financial advice. This guide explains how stocks and shares ISAs work based on current HMRC rules as of April 2026. It is for information only and does not constitute personal financial advice. Individual circumstances vary, consider speaking to an independent financial adviser before making any investment decision. The value of investments can go down as well as up and you may get back less than you invest. Always check gov.uk/individual-savings-accounts for the latest rules.