Cash ISA vs Stocks and Shares ISA: Which Is Right for You in 2026?
Cash ISA or stocks and shares ISA? How the £20,000 allowance works, the April 2027 cash ISA cap, and which suits your money.
TL;DR: A cash ISA pays tax-free interest with no risk to your capital and £120,000 FSCS protection; a stocks and shares ISA invests your money, so it can grow more, or fall. You get a £20,000 ISA allowance for 2026/27 to split how you like, but from April 2027 under-65s can only put £12,000 a year into cash ISAs. If you might need the money within five years, keep it in cash.
How the ISA allowance works in 2026/27
Every UK adult gets a £20,000 ISA allowance each tax year (6 April 2026 to 5 April 2027). You can put the whole £20,000 into one ISA or split it across cash ISAs, stocks and shares ISAs, innovative finance ISAs and Lifetime ISAs. Since April 2024 you can even open and pay into more than one ISA of the same type in the same year, as long as the total stays within £20,000.
The big change to know: from 6 April 2027, the cash ISA subscription limit drops to £12,000 a year for savers under 65. The overall £20,000 allowance doesn’t change, but the other £8,000 would need to go into a stocks and shares ISA (or innovative finance ISA) to stay tax-free. Savers aged 65 and over keep the full £20,000 cash allowance, and existing cash ISA balances are unaffected, the cap applies to new contributions only. In other words, for under-65s, 2026/27 is the last tax year you can shelter a full £20,000 in cash.
Cash ISA vs stocks and shares ISA at a glance
| Cash ISA | Stocks & shares ISA | |
|---|---|---|
| Tax on gains/interest | None | None |
| Risk to your money | None (up to FSCS limit) | Yes, investments can fall |
| FSCS protection | £120,000 per person, per institution | £85,000 if the platform fails (not market losses) |
| Access | Usually easy access or fixed terms | Usually a few days to sell and withdraw |
| Best for | Money needed within 5 years; emergency funds | Money you won’t touch for 5+ years |
Who should choose a cash ISA?
Anyone saving for something within the next few years, a house deposit top-up, a wedding, or your emergency fund. Your capital is safe, interest is tax-free, and cash ISAs now carry £120,000 FSCS protection per person per institution (raised from £85,000 in December 2025). The trade-off: inflation may erode what your money buys over long periods.
Who should choose a stocks and shares ISA?
MoneyHelper’s rule of thumb: only invest money you won’t need for at least five years, and accept its value can go down as well as up. Over long periods, markets have historically beaten cash, but “historically” is doing heavy lifting in that sentence, and there are no guarantees. If a market dip would force you to sell at the wrong time (because you need the cash), you shouldn’t be invested.
Can you have both?
Yes, most people eventually do. A common setup: emergency fund and short-term savings in easy-access or fixed-rate cash savings (some inside a cash ISA for the tax break), and long-term money in a stocks and shares ISA. With the April 2027 cash cap coming, splitting deliberately matters more than it used to. Also see our best savings account guide when comparing homes for the cash portion.
A quick word on Lifetime ISAs
If you’re 18–39 and saving for a first home (worth up to £450,000) or retirement, a Lifetime ISA adds a 25% government bonus on up to £4,000 a year, but withdrawals for anything else attract a 25% charge, which can leave you with less than you put in. It counts toward your £20,000 allowance.
Best ISA interest rates right now
Cash ISA interest rates move constantly. Here is a snapshot for October 2026; for the full tables, refreshed every month, see our best cash ISA rates guide.
| Account | Rate (AER) | Type |
|---|---|---|
| Trading 212 Cash ISA | 4.80% variable (includes 12-month bonus) | Easy access |
| Plum Cash ISA | 4.71% variable (includes 12-month bonus) | Easy access |
| Shawbrook Bank | 4.97% fixed | Fixed 1 year |
| Tandem Bank | 5.08% fixed | Fixed 2 years |
| Tandem Bank | 5.13% fixed | Fixed 3 years |
| Leek Building Society | 5.30% fixed | Fixed 5 years |
Rates correct for October 2026 and change frequently. The full rates guide is refreshed monthly.
Frequently asked questions
Do I pay tax on ISA interest or gains?
No, that’s the whole point. Interest, dividends and capital gains inside any ISA are free of UK tax.
What happens to my existing cash ISA when the £12,000 cap starts?
Nothing. The cap applies to new subscriptions from 6 April 2027; money already inside your cash ISA stays sheltered.
Is my stocks and shares ISA protected if my investments lose value?
No. FSCS investment protection (£85,000) covers you if the platform or provider fails, it never covers market losses.
Can I move money between ISAs?
Yes, via an ISA transfer, which preserves the tax-free status. Don’t just withdraw and re-deposit, that uses up allowance.
Allowance figures and rules checked 30 September 2026; tax rules can change. Sources: Barclays ISA guide, MoneyHelper: should I save or invest, MoneySavingExpert: safe savings.
Part of our Savings and Interest hub.
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