Cash ISA vs Stocks and Shares ISA: which is right for you?

When you decide where to put this year's ISA allowance, one of the most common questions is whether to put your money in a Cash ISA or a Stocks and Shares ISA. Both offer tax-free returns, but they work very differently — and choosing the wrong one could mean missing out on growth or losing money you couldn't afford to risk.

A Cash ISA works like a savings account but with tax-free interest. Your money is protected by the FSCS up to £120,000 per person per authorised firm, and you know exactly what rate you're getting. Rates change often, so compare current easy-access and fixed Cash ISAs on MoneySavingExpert or Which?. Fixed-rate options can offer more if you're willing to lock your money away for a year or two. Cash ISAs are ideal if you need the money within the next 1-3 years — for a house deposit, wedding, or emergency fund.

A Stocks and Shares ISA invests your money in funds, shares, bonds, or a mix. Returns depend on market performance, which means they can be much higher than cash — historically, global equity funds have returned around 8-10% per year on average — but they can also fall. You could end up with less than you put in, especially over short periods. This type of ISA suits people with a 5+ year time horizon who can stomach short-term volatility.

Timeline matters most. Money you need within 3 years should almost always go in cash. Money you won't touch for 5+ years has historically done better in the market. Risk tolerance is personal — if seeing your balance drop 15% would keep you up at night, stocks aren't for you right now. And don't forget fees: many Stocks and Shares ISA platforms charge annual fees of 0.15% to 0.45%, plus fund charges on top, which eat into returns.

Yes. You can put some of your £20,000 allowance in a Cash ISA and the rest in a Stocks and Shares ISA within the same tax year. This is a sensible approach for many people: keep your emergency fund and short-term savings in cash, and invest the rest for long-term growth. Just make sure the total across all ISA types doesn't exceed £20,000. From 6 April 2027, under-65s will be able to put at most £12,000 of that into Cash ISAs, with the rest available for Stocks and Shares (or Innovative Finance) ISAs.

There's no universally correct answer. If you're saving for something specific in the next few years, cash is king. If you're building long-term wealth and won't need the money for a decade, investing will almost certainly outperform cash over that period. The worst choice is doing nothing and letting your ISA allowance expire. Pick one, fund it, and adjust your strategy next year if needed.