ISA tax calculator
ISA tax calculator: how much tax does an ISA save?
The same investments held outside an ISA can be taxed on their dividends and on the gains when you sell. Inside an ISA, neither applies. Put in your numbers and see the difference for one year.
How much tax does an ISA save?
The same investments held outside an ISA can be taxed on their dividends and on the gains when you sell. Inside an ISA, neither applies. Here's the difference for one year.
Your numbers
Tax an ISA would save this year
£0
How to read this
Rates and allowances used, for 2026/27 at the time of writing: a £500 dividend allowance, then dividend tax of 10.75% (basic), 35.75% (higher) or 39.35% (additional); a £3,000 Capital Gains Tax allowance, then 18% for basic-rate taxpayers and 24% for higher and additional. It assumes you haven't used those allowances elsewhere, and treats a basic-rate taxpayer's whole gain at 18%, although a large gain can push part of it to 24%. Check gov.uk for the current figures. And the saving repeats every year the money stays wrapped, which is the real point. More in what a Stocks and Shares ISA is.
How it works
What an ISA saves you
Outside an ISA, investments can be taxed twice: on the dividends they pay and on the gains when you sell. Inside a Stocks and Shares ISA there’s no tax on either, and nothing to report on a tax return.
Two taxes outside
Dividends above the £500 dividend allowance are taxed at your dividend rate. Gains above the £3,000 Capital Gains Tax allowance are taxed when you sell.
The calculator works out both for one year.
Allowances have shrunk
The dividend allowance was £2,000 until April 2023, and the Capital Gains Tax allowance was £12,300.
So more ordinary investors now pay tax on investments held outside an ISA than a few years ago.
The saving repeats
The dividend saving comes round again every year the money stays inside the ISA, and the gains saving grows as the investments grow.
More in do you pay tax on an ISA?.
Questions
Common questions
Quick answers about the figures. For your own circumstances, gov.uk and your provider have the details.
Do I pay tax on ISA withdrawals?
No. Money taken out of an ISA is tax-free and doesn’t need to be declared.
Why is the basic-rate gain all at 18%?
To keep it simple. In reality, a large gain added to your income can push part of it into the higher band, where the rate is 24%.
What about Scotland?
Dividend tax and Capital Gains Tax use the UK rates wherever you live, but your band depends on your income, so choose the band your total income falls in.
Rates used
All rates are at the time of writing and were checked at source on 3 November 2026. They’re updated each year on 6 April, and after any Budget that changes them.
| What | 2026/27 | Source |
|---|---|---|
| Dividend allowance | £500 a year | gov.uk: Tax on dividends |
| Dividend tax above the allowance | Basic rate 10.75%; higher rate 35.75%; additional rate 39.35% | gov.uk: Tax on dividends |
| Capital Gains Tax allowance | £3,000 a year | gov.uk: Capital Gains Tax allowances |
| Capital Gains Tax on shares | 18% within the basic-rate band; 24% above it | gov.uk: Capital Gains Tax rates |
Other calculators
New to ISAs?
Read the sixteen articles in order.
Getting Started takes you from the basics to opening your ISA, then the principles that keep you invested and how wealth builds over time.
Go to Getting StartedAll results are illustrations, not forecasts, and not financial advice. They assume steady rates that real markets never deliver. The value of investments can go down as well as up, and you can get back less than you put in. Allowances, tax rates and ISA rules can change, so always check gov.uk for the current figures.
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