What is a Stocks and Shares ISA?
A Stocks and Shares ISA is an ordinary dealing account with a tax-free wrapper around it. You can pay in up to £20,000 per tax year (2026/27, across all your ISAs), buy the same UK and foreign shares, ETFs and funds as anywhere else — and inside the ISA there is no capital gains tax and no dividend tax, ever. There is nothing to report to HMRC, and you can take the money out whenever you like.
One red dot: the tax only comes on the day you sell.
How it works
- £20,000 a year. That is the total for all ISA types together (cash, stocks and shares, Lifetime, Innovative Finance). From 6 April 2027 the cash ISA part is capped at £12,000 for under-65s — the Stocks and Shares ISA limit is unaffected.
- No tax inside, ever. Gains, dividends and interest inside the ISA are all tax-free, however large they get. The allowance is on what you put in, not on what it grows to.
- Take it out any time. An ISA is not a pension: you can withdraw whenever you want. With a "flexible" ISA you can even put the money back in the same tax year without using more allowance.
- Same shares, same costs. The broker's commission, platform fee and 0.5 % stamp duty on UK shares apply exactly as in an ordinary account. Most brokers offer the ISA for the same price.
- One provider per type per year used to be the rule; since 2024 you can pay into several Stocks and Shares ISAs in the same year, as long as the total stays within £20,000.
The worked example
You pay £10,000 into a Stocks and Shares ISA and buy shares. Over ten years they grow to £25,000 and pay £3,000 in dividends along the way. You sell everything: £0 tax, nothing to declare.
The same in an ordinary dealing account, for a higher-rate taxpayer: dividends above the allowance taxed at 35.75 %, and the £15,000 gain minus £3,000 exemption at 24 % = £2,880 in CGT alone.
Why it matters for a beginner
For most people starting out in the UK the ISA is simply the default place to hold shares: same shares, same broker, no tax and no paperwork. The limits only bite once you save more than £20,000 a year. It is not a recommendation — Kiggo never tells you where to put your money — but it is the reason the tax pages for the UK are shorter than for most other countries: inside an ISA, the other two pages do not apply.
The typical beginner's mistake
Keeping shares in an ordinary dealing account for years while the ISA allowance goes unused every April — and then paying capital gains tax to move them. Unused allowance cannot be carried forward.
How you see it in Kiggo
Kiggo does not know which account your shares are in — it shows the same numbers either way. In Kiggo's guide for the UK, the ISA is the step "Start with a Stocks and Shares ISA". Kiggo does not calculate your tax and does not recommend a provider.
Related terms
Frequently asked questions
What is the ISA allowance for 2026/27?
£20,000 per person per tax year, across all ISA types. From 6 April 2027 no more than £12,000 of it may go into a cash ISA for under-65s; the Stocks and Shares limit stays at £20,000.
Can I hold US shares in a Stocks and Shares ISA?
Yes — most brokers allow foreign shares and ETFs. US dividends still lose 15 % US withholding tax (with a W-8BEN form), which the ISA cannot recover, but there is no UK tax on top.
What happens if I withdraw money from my ISA?
Nothing tax-wise — withdrawals are tax-free. But unless your ISA is flexible, the money you took out still counts against this year's allowance if you want to put it back.
Kiggo explains — Kiggo does not advise. We never tell you what to buy or sell, and key figures can only be compared between companies in the same industry. The decision is yours. Last updated 2026-09-07.
Written by Claus Frisch, founder of Kiggo. Not an adviser, not a bank — Kiggo explains, you decide.
