The three taxes an ISA shelters you from
In the UK, your savings and investments are normally exposed to three separate taxes. An ISA removes all three on everything held inside the wrapper:
- Income tax on interest — normally only some interest is tax-free (the Personal Savings Allowance, £1,000 for basic-rate taxpayers). Inside an ISA, all interest is tax-free.
- Dividend tax — outside an ISA only the first £500 of dividends is tax-free in 2026/27, then 10.75% / 35.75% / 39.35% applies. Inside an ISA, dividends are completely tax-free.
- Capital gains tax — outside an ISA you have a £3,000 annual exempt amount in 2026/27, then gains are taxed at 18% / 24%. Inside an ISA, all gains are tax-free.
You also do not declare ISAs on a Self Assessment tax return. That makes an ISA one of the simplest tax shelters available in the UK.
How much can you put in an ISA?
Every adult gets a £20,000 annual ISA allowance for the 2026/27 tax year (6 April 2026 – 5 April 2027), split however you like across your ISAs. The allowance does not carry over — unused allowance is lost at the end of the tax year.
| ISA type | What it holds | Annual limit (2026/27) |
|---|---|---|
| Cash ISA | Tax-free interest on savings | £20,000 (shared) |
| Stocks & Shares ISA | Tax-free investment growth | £20,000 (shared) |
| Lifetime ISA | 25% bonus for a first home or later life | £4,000 |
| Innovative Finance ISA | Peer-to-peer loans | £20,000 (shared) |
| Junior ISA | For children under 18 | £9,000 |
GOV.UK · 2026/27 — from 6 April 2027, the Cash ISA limit becomes £12,000 for investors under 65 (those 65 and over keep £20,000).
Why ISAs beat a normal savings or investment account
The difference is easy to underestimate because it grows over years. A basic-rate taxpayer outside an ISA can earn only £1,000 of tax-free interest a year, and only £500 of tax-free dividends. Above those thresholds, tax starts eating returns every single year. Inside an ISA, the entire pot compounds tax-free — which is why an ISA is usually the right first home for long-term savings and investing. Model it with the ISA calculator →
Can you withdraw money tax-free?
Yes. With a Cash, Stocks & Shares or Innovative Finance ISA you can normally take money out whenever you like — and the money you withdraw is not taxed. Once the new tax year starts on 6 April, you get your full £20,000 allowance back and can pay it back in.
The one important exception is a Lifetime ISA: money can only be used for a first home up to £450,000 or after age 60 (or in limited cases of terminal illness). Any other withdrawal is hit with a 25% charge, which claws back the government bonus.
Is an ISA worth it even if returns are modest?
Generally yes, but it depends. If you are a basic-rate taxpayer with less than £1,000 of interest a year, a Cash ISA and a normal savings account may look similar before your allowance is used up. Where ISAs pull ahead is over the long term: dividends, capital gains, and interest above the allowances all keep compounding tax-free year after year. If you are a higher-rate taxpayer, the benefit is larger still.