Stocks and Shares ISA Tax: What's Tax-Free and What Changes in 2027

Everything inside a stocks and shares ISA is free of UK Income Tax and Capital Gains Tax: dividends, interest, bond coupons and growth all build up untaxed, and withdrawals are tax-free whatever the amount. You do not put ISA income or gains on a Self Assessment return, and you do not tell HMRC about them at all. The much-discussed change coming in April 2027 caps how much of the annual allowance can go into cash ISAs for people under 65 — it does not tax stocks and shares ISAs or cut the overall £20,000 limit.

• No tax inside, no tax out: no Income Tax on dividends or interest, no Capital Gains Tax on profits, no tax on withdrawals.
• Nothing to declare: ISA income and gains never appear on a tax return, and they do not count towards your adjusted net income.
• £20,000 a year is the total ISA allowance across all your ISAs in 2026/27, and it does not carry forward.
• The 2027 change is a cash ISA sub-limit of £12,000 for under-65s, with the rest of the £20,000 available for stocks and shares.
• Limits still apply: no loss relief, no relief from foreign withholding tax, 0.5% stamp duty reserve tax on most UK share purchases, and ISAs still count for Inheritance Tax.

What is tax-free inside a stocks and shares ISA

An ISA is a wrapper, not an investment. Once money is inside it, three separate taxes stop applying to what happens in there:

• Dividend tax. Outside an ISA, dividends above the £500 dividend allowance are taxed at 10.75% (basic rate), 35.75% (higher rate) or 39.35% (additional rate). Inside an ISA, the rate is nil and the dividend allowance stays intact for shares you hold elsewhere.
• Income Tax on interest. Cash held in the ISA, plus interest from bonds and bond funds, is untaxed. Your Personal Savings Allowance (£1,000 basic rate, £500 higher rate, nil additional rate) is untouched by it.
• Capital Gains Tax. Gains are ignored entirely, so the £3,000 annual exempt amount and the 18% and 24% CGT rates never come into it. You can rebalance, switch funds or sell your whole portfolio without a CGT calculation.

These reliefs apply the same way across the UK. Scottish income tax rates apply to non-savings, non-dividend income only, so a Scottish taxpayer pays the same dividend and CGT rates as everyone else — and the same nil rate inside an ISA.

What the shelter is actually worth

Take a £50,000 portfolio yielding 3.5%, so £1,750 of dividends in the year, which you then sell for a £12,000 gain. Here is the tax bill outside an ISA for a higher-rate taxpayer:

A basic-rate taxpayer with the same numbers would pay £134.38 on the dividends (£1,250 at 10.75%) and, if the gain sat inside the basic-rate band, £1,620 on the gain (£9,000 at 18%) — £1,754.38 in total. Either way the ISA figure is zero, and it stays zero in every future year the money remains inside the wrapper. Our ISA calculator and investment calculator let you run your own numbers over a longer period, where the compounding effect of untaxed dividends does most of the work.

Do you have to declare a stocks and shares ISA to HMRC?

No. There is no box on the Self Assessment return for ISA interest, ISA dividends or ISA gains, and you do not report ISA withdrawals either. Your provider handles the reporting to HMRC behind the scenes, and no tax certificates are needed.

Three practical consequences follow from that:

• No CGT reporting. Outside an ISA you may need to report gains even when no tax is due, for example if your proceeds are large relative to the annual exempt amount. Inside an ISA, there is nothing to report at any level.
• Adjusted net income is unaffected. ISA income does not push you towards the Personal Allowance taper that starts at £100,000, or into the High Income Child Benefit Charge zone between £60,000 and £80,000. Taxable dividends and interest do.
• Your tax code stays clean. HMRC sometimes collects tax on taxable savings interest through a coding adjustment. Interest earned inside an ISA should never appear there — if it does, the code is wrong.

One thing you may still need to tell HMRC about: if you accidentally pay more than £20,000 into ISAs in a tax year, or open two ISAs of a type in a way your providers cannot correct, contact HMRC rather than trying to fix it yourself. Excess subscriptions are usually stripped out of the wrapper, and the income on them becomes taxable.

ISA withdrawals: is there any tax?

There is no ISA withdrawal tax. Take out £500 or £150,000 and the amount is yours in full, with no Income Tax, no CGT and nothing to declare. This is the main difference from a pension, where 25% is normally tax-free and the rest is taxed as income when drawn.

The catch is the allowance, not the tax. What happens when you put money back depends on whether your ISA is a flexible ISA:

• Flexible ISA: money you withdraw can be replaced in the same tax year without using up any more of your £20,000. Withdraw £5,000 in June and repay £5,000 in February and your allowance is untouched.
• Non-flexible ISA: the replacement counts as a fresh subscription. Withdraw £5,000 and pay it back and you have used £5,000 of the £20,000.

Flexibility is a provider choice and many stocks and shares ISAs are not flexible, or are flexible only for the cash part of the account. Check before you take money out and plan to return it in the same tax year.

Two other points on getting money out. Selling investments inside the ISA is not a withdrawal — the proceeds sit as cash in the wrapper and stay sheltered. And a Lifetime ISA is different: withdrawals before age 60 for anything other than a first home or on ill-health grounds carry a government withdrawal charge, which can leave you with less than you put in.

The April 2027 cash ISA change, explained

This is where most of the confusion sits, so to be plain about it: the change announced for April 2027 restricts cash ISA subscriptions for people under 65. It does not introduce tax on stocks and shares ISAs, does not touch existing balances, and does not reduce the £20,000 overall allowance.

From April 2027, the position is expected to be:

• The total ISA allowance remains £20,000 a year across all ISA types.
• For savers under 65, a maximum of £12,000 of that can go into cash ISAs. The remaining £8,000 can still be used, but only in a stocks and shares ISA (or another non-cash ISA type).
• Savers aged 65 and over keep the ability to use the full £20,000 in cash.
• Money already held in cash ISAs from earlier years is not affected and keeps its tax-free status. Transfers of old cash ISA money between providers are not new subscriptions.

The practical effect for an investor is simple: 2026/27 is the last full tax year in which an under-65 saver can put the whole £20,000 into cash, and from 2027/28 the allowance tilts towards investing. If you were already using your allowance for shares and funds, nothing about your ISA tax position changes. We cover the mechanics in detail in the guide to the £12,000 cash ISA limit from April 2027, and the wider picture for this tax year in ISA changes for 2026/27.

Worth remembering how the £20,000 is shared out in the meantime: a Lifetime ISA takes a maximum of £4,000 a year and that £4,000 counts inside the £20,000 total. Junior ISAs have their own separate allowance and do not use the adult £20,000.

The downsides and the limits of the shelter

An ISA removes three taxes, not all of them. The gaps matter if you are choosing between an ISA and a taxable account.

No loss relief

Because gains inside an ISA are ignored, losses are ignored too. A £10,000 loss on shares held outside an ISA can be set against other capital gains, and carried forward indefinitely if claimed. The same loss inside an ISA is simply gone.

Foreign withholding tax still bites

An ISA is a UK tax shelter, so it has no effect on tax deducted overseas. US dividends typically suffer 15% withholding once a W-8BEN form is in place with your provider (30% without it), and that 15% cannot be reclaimed or credited because there is no UK tax to set it against. Other countries apply their own rates.

Stamp duty on share purchases

Buying UK shares generally attracts 0.5% stamp duty reserve tax, and holding them in an ISA does not change that. It is charged at the point of purchase, not on the ISA.

ISAs are not Inheritance Tax free

ISA balances form part of your estate on death, so they can be taxed at 40% above the available nil-rate band of £325,000, plus the residence nil-rate band of £175,000 where it applies. A surviving spouse or civil partner can, however, claim an additional permitted subscription equal to the value of the deceased's ISAs, which lets the money stay wrapped.

The allowance is use-it-or-lose-it

Unused allowance does not carry forward to the next year. And moving existing taxable holdings into an ISA means selling them first — a "bed and ISA" — which is a disposal for CGT in its own right, so the gain has to fit within the £3,000 annual exempt amount or tax is due on the way in.

What to do next

If you want to see what the wrapper is worth over 10 or 20 years rather than one, run your contributions through the ISA calculator, then compare the same numbers in a taxable account with the investment calculator. If you hold shares or funds outside an ISA, it is also worth checking the dividend and CGT position on those first — that is where a bill can appear without warning. The official rules, including the current allowance and the list of ISA types, are on GOV.UK's ISA pages.