An ISA is an account where your savings and investments grow free of UK tax: no tax on interest, dividends or gains, and nothing to report to HMRC. There are three main kinds, and in the 2026/27 tax year you can put up to £20,000 in total across all of them. My view: once you have an emergency fund, a Stocks & Shares ISA is the one most people should open. If you're under 40 and might buy your first home, add a Lifetime ISA. I'd rarely choose a Cash ISA.
What's the difference between the three ISAs?
They differ in what they can hold, how much you can pay in, and when you can take money out.
| Stocks & Shares ISA | Cash ISA | Lifetime ISA | |
|---|---|---|---|
| What it holds | Funds, shares and cash | Cash only | Cash or investments, depending on the provider |
| Yearly limit | £20,000 | £20,000 | £4,000 |
| Who can open one | 18 or over | 18 or over | 18 to 39 |
| Government bonus | None | None | 25%, up to £1,000 a year |
| Taking money out | Any time | Any time, unless it's a fixed-rate account | For a first home, from age 60, or if terminally ill; otherwise a charge applies |
The £20,000 is one allowance shared between all your ISAs, so you could, for example, put £4,000 in a Lifetime ISA and £16,000 in a Stocks & Shares ISA.
Is a Stocks & Shares ISA better than a Cash ISA?
In my view, yes. A Stocks & Shares ISA can hold cash, but a Cash ISA can't hold shares or funds. So a Stocks & Shares ISA can do everything a Cash ISA does, and more.
The way to hold "cash" in a Stocks & Shares ISA is a money market fund: a low-risk fund that holds very short-term loans to banks and governments and pays interest, much like a savings account. When you're ready to invest, the money is already in the right account, with no transfer needed.
The October 2026 Budget kept this option open. The government had planned, from April 2027, to cut the Cash ISA limit to £12,000 for under-65s, charge 22% on interest earned on cash held in a Stocks & Shares ISA, and stop under-65s moving money from a Stocks & Shares ISA to a Cash ISA. All three plans were scrapped.
To be fair to Cash ISAs, they have two advantages. You can fix a rate for a year or more, and bank deposits are protected by the Financial Services Compensation Scheme up to £120,000 per bank. A money market fund isn't a bank deposit, so its value isn't guaranteed, though it's designed to be very stable.
Why use an ISA rather than a general investment account?
Because outside an ISA, your investments can be taxed. In 2026/27, dividends above £500 a year are taxed at 10.75%, 35.75% or 39.35% depending on your income, and gains above £3,000 a year when you sell are subject to Capital Gains Tax. Inside an ISA, there's none of that, and no tax return to fill in.
For example, if you sell investments outside an ISA with a £10,000 gain, £7,000 of it is taxable. The same gain in an ISA is tax-free. That's why I think anyone with savings beyond their emergency fund should use a Stocks & Shares ISA before a general account.
Should you open a Lifetime ISA?
If you're 18 to 39 and might buy your first home, I think yes. The government adds 25% to what you pay in: put in £4,000 a year and you get £1,000 free. You can use it for a first home costing up to £450,000, or take it out from age 60. You have to open it before you turn 40 and can pay in until 50. The account must have been open for at least 12 months before you use it for a home.
The catch has always been the withdrawal charge. Take money out for any other reason and you pay 25% of the withdrawal, which wipes out the bonus and some of your own money too. That used to apply if your first home cost more than £450,000, which is easy to exceed in London.
The October 2026 Budget fixed most of that. From 29 October 2026, if you use a Lifetime ISA towards a first home costing more than £450,000, the charge is 20% instead of 25%. That's roughly just the bonus back. MoneySavingExpert's example: pay in £4,000, get a £1,000 bonus and £250 of growth, and the account is worth £5,250. A 20% charge takes £1,050, leaving you £4,200, more than you paid in. Under the old 25% charge you'd have got about £3,940 back. In my view this makes the Lifetime ISA a much better deal, because the worst case if your home ends up over the cap is losing the bonus, not your own money.
Withdrawals for anything other than a first home, retirement from 60 or terminal illness still carry the 25% charge, so only use a Lifetime ISA for money you're fairly sure is for a home or retirement. If it's for retirement, compare it with a pension first, especially if your employer pays into one.
From April 2029, a new First Time Buyer ISA will replace the Lifetime ISA for new savers. It will be for homes only, not retirement. If you want a Lifetime ISA, you'll need to open one before then; existing accounts carry on.
Where should beginners open a Stocks & Shares ISA?
Look for low fees. With a small portfolio, a fixed account fee can cost you more than the investments themselves. Trading 212 is a good option for beginners because it charges no account fee. Vanguard is a great platform, but it charges £4 a month below £32,000 invested: £48 a year, which is 0.96% of a £5,000 portfolio. That makes it better suited to larger portfolios. I compare the two in Vanguard vs Trading 212.
Neither offers a Lifetime ISA, so if you want one you'll need a separate provider.
Which ISA should you open?
In the order I'd do it:
- Build an emergency fund of easy-access cash first, so you don't have to sell investments when something goes wrong.
- Open a Lifetime ISA if you're 18 to 39 and might buy a first home.
- Put the rest in a Stocks & Shares ISA, invested in low-cost index funds, with a money market fund for money you'll need in the next few years.
I'd rarely choose a Cash ISA: a Stocks & Shares ISA can do the same job and much more.
This is my general view, not personal advice: it can't take account of your circumstances, and investments can fall as well as rise.