Stocks and shares ISAs explained: what they are and how to use one

Key takeaways

• A stocks and shares ISA is an account you can use to hold investments, not an investment on its own

• Within the ISA rules, you won’t pay UK tax on eligible gains or income from investments held inside it

• Your investments can still rise and fall in value, so it’s best suited to money you can leave invested for several years

If you've started looking into investing, you've probably seen the letters "ISA" everywhere – but it might not be clear to you what that means. Here's a key thing to know: a stocks and shares ISA isn't an investment in itself. It's an account you use to invest with. Think of it as a wrapper – a box that you can put investments inside, where they get special tax treatment. The investments might still rise and fall in value like any others; the ISA just changes how you’re taxed on those holdings. This guide explains what an ISA is, what you can hold in it, how much you can pay in, and what to check before opening one.

What is a stocks and shares ISA?

A stocks and shares ISA is an Individual Savings Account (ISA) that you can use for investing, rather than just hanging-on to cash. You use it to hold investments that can rise and fall in value, and – within the rules – you won't pay UK tax on what they earn.

The most important point to remember is this: the stocks and shares ISA is the account, not the thing you buy inside it. Think of it like a trip to the supermarket. The platform you sign up with is the supermarket itself, your ISA is the basket you carry around, and the investments on the shelves – funds, shares, and so on – are what you choose to drop in. Opening one doesn't mean you've invested in anything yet – you still need to decide what goes inside.

How is a stocks and shares ISA different from other ISAs?

Different ISAs are built for different jobs. A stocks and shares ISA holds investments that can rise and fall in value, and is designed with the aim of growing your money over the longer term. A cash ISA holds cash savings and pays interest, much like a regular savings account. They do quite different things – one is for saving, the other for investing.

There are a few other ISA types too – such as a Lifetime ISA, Junior ISA, and Innovative Finance ISA – each one built for a specific goal or group of people. We won't cover them all here, so let’s keep the focus on the stocks and shares ISA, which is the one most beginners meet first.

What can I hold inside a stocks and shares ISA?

These typically hold a range of investments: funds, exchange-traded funds (ETFs), individual shares, and bonds. Many beginners lean towards funds or ETFs, because a single one can hold lots of different investments at once – that makes them an easy way to diversify, or spread your money around, without picking loads of individual stocks yourself.

Exactly what's available depends on the investment platform you choose. Some ISA providers offer a huge range; others keep things simpler with a shorter, more ready-made list. It's worth a quick look before you open an account, though, to check you can access the kind of investments you have in mind.

How much can I pay in?

Each tax year, you can pay in up to the ISA allowance, which is £20,000 for the 2026/27 tax year. The key thing to understand is that this is a single, shared limit across all the ISAs you pay into – not £20,000 for each one. So if you put £5,000 into a cash ISA and £8,000 into a stocks and shares ISA in the same year, you've used £13,000 of your £20,000 allowance, leaving just £7,000 to use across any other ISAs before the tax year ends.

Two other things are worth knowing:

1. The allowance resets at the start of each new tax year (6 April)

2. And any allowance you don't use doesn't roll over – once the tax year ends, that year's unused amount is gone

It's also worth flagging a change that’s on the horizon. From 6 April 2027, the amount that people under 65 can pay into a cash ISA will drop from £20,000 to £12,000. The overall £20,000 allowance, and the stocks and shares ISA limit specifically, will both stay the same, though. In practice, that means under-65s who want to use their full allowance will need to put at least part of it somewhere other than cash, for example into investments. People aged 65 and over keep the full £20,000 cash ISA allowance. The change affects only new contributions from that date, so any savings already in a cash ISA won’t be impacted.

What are the tax benefits?

Inside a stocks and shares ISA, you don't pay UK tax on eligible gains or income from your investments. There are two pieces of jargon worth unpacking there:

• A gain is the money you make if you sell an investment for more than you paid for it. For example, if you buy shares for £1,000 and later sell them for £1,300, your gain is £300.

• Income is money some investments pay out along the way – such as dividends from shares or funds.

Outside an ISA, both can be taxable above certain limits.

Please note: The tax treatment of investments can change and is subject to individual circumstances.

Picture a pot you pay into for years: the dividends it pays out along the way, and any profit when you eventually sell, are generally yours to keep rather than partly taxed. This matters more as your pot grows – a small gain might not be taxed much either way, but over years of compounding, the shelter can become genuinely useful. As a bonus, you don't need to report ISA investments on a tax return, which is one less thing to keep track of.

Can I take money out?

Usually, yes – but it's worth checking your provider's specific rules first. Some ISAs (like the one offered by Investments by MoneySupermarket) are "flexible", which means you can take money out and put it back in the same tax year without it eating into your allowance again. Others aren't, so any money you replace counts as a fresh payment against your allowance.

One practical caveat: taking money out often means selling investments first, and that can take a little time. In many cases, the investment’s price will have moved by the time the sale completes – so the amount you get isn't fixed the moment you decide to withdraw.

How do I start investing through an ISA?

The basic path is short: open the ISA, pay in some money, choose an investment, and confirm the order. The step beginners most often miss is that paying money into the ISA isn't the same as investing it. Until you choose something to buy, your money usually just sits there as cash inside the account.

A sensible starting point is an amount you're comfortable leaving invested for several years (think at least five years) – because, like any investment, a stocks and shares ISA is best suited for money you won't need at a moment’s notice.

What should I keep in mind?

A stocks and shares ISA can be a useful home for your investments, but it's worth being clear about what it does and doesn't do. It doesn't remove investing risk – the investments inside can still rise and fall, and you could get back less than you put in. What’s more, tax rules can change over time, and their impact depends on your personal circumstances.

The ISA account helps with the tax side, but it doesn't make your choices for you. Whatever you hold inside, it still needs to match your goals, your timeframe, and how comfortable you are with the value moving around.

This information is for education only. It’s not financial advice or a personal recommendation.

Moneysupermarket.com Investments Limited is an appointed representative of P1 Investments Services Limited, which is authorised and regulated by the Financial Conduct Authority (FCA FRN 752005).