The Stocks and Shares ISA Explained
How the UK's main tax-efficient investment wrapper works, and how to use it well.
A Stocks and Shares ISA (Individual Savings Account) is the UK's principal tax wrapper for investments, letting you hold shares, ETFs and funds while shielding any gains and income from tax.
The annual ISA allowance
For the 2026/27 tax year, the total ISA allowance is £20,000 per person, shared across all the ISA types you hold (cash, stocks and shares, innovative finance and Lifetime ISA). You can split this allowance across more than one type of ISA in the same tax year, but not exceed the £20,000 total.
What the ISA shelters you from
Investments held within a Stocks and Shares ISA are completely exempt from both Capital Gains Tax and dividend tax, with no reporting requirement to HMRC — a meaningful benefit given the Capital Gains Tax annual exempt amount is now just £3,000 and the dividend allowance only £500.
The allowance doesn't carry forward
Unlike the pension annual allowance in some circumstances, unused ISA allowance cannot be carried forward to a future tax year — if you don't use some or all of your £20,000 by 5 April, it's gone for good.
Transfers between providers
Moving an existing ISA from one provider to another, done correctly through an ISA transfer (not by withdrawing and rebuying), is not treated as a new subscription and doesn't use up your annual allowance.
"Bed and ISA"
Investors holding shares or funds outside an ISA sometimes use a strategy known as "Bed and ISA" — selling the investment and immediately repurchasing it within an ISA — to bring future growth under the ISA's tax shelter. This still crystallises any gain on the original sale, which counts towards your CGT annual exempt amount for that year.