Capital gains tax on shares
Tax on a gain you have already worked out: stacked on your income, sliced at the basic-rate boundary, with the annual exempt amount shown — and with the share matching this tool does not do said plainly, not buried.
Calculator
The tax on your share disposal
Capital gains tax on this disposal: £4,063.80
From your income to your taxable income
| Income before tax | £50,000.00 |
|---|---|
| Less personal allowance used | −£12,570.00 |
| Taxable income — what your gain stacks on | £37,430.00 |
| Income tax on that income (England or Northern Ireland) | £7,486.00 |
The personal allowance is worked out by the same engine that computes income tax, so it tapers away above £100,000 without this page having to know that. Income tax is shown for context only — it is not part of the capital gains figure above.
Your gain stacks on top of your income
The basic rate for gains runs to £37,700 of taxable income. Yours is £37,430.00, which leaves £270.00 of basic-rate band for the gain to fall into. Everything above that is taxed at the higher rate — the same disposal can be taxed at two rates at once.
That room is measured in taxable income, not in pay. Another £270.00 of income before tax would use up what is left of it, and after that the whole gain meets the higher rate.
| Band | Gain in this band | Rate | Tax |
|---|---|---|---|
| Basic rate | £270.00 | 18.00% | £48.60 |
| Higher rate | £16,730.00 | 24.00% | £4,015.20 |
| Total | £17,000.00 | £4,063.80 |
Annual exempt amount
| Exempt amount for 2026/27 | £3,000.00 |
|---|---|
| Used by this disposal | £3,000.00 |
| Left unused | £0.00 |
| Chargeable gain after it | £17,000.00 |
The exempt amount is deducted before anything is taxed and it does not use up any of your basic-rate band. It is one allowance for the whole tax year across every disposal you make, and this page has deducted all of it against the single disposal above — see the third point below if that is not your only one. Unused exemption cannot be carried forward.
Three things this figure does not know
It does not work out the gain, and for shares that is where it usually goes wrong
There is no share matching here — no same-day rule, no 30-day bed-and-breakfast rule, no s104 pooling — so the gain you enter has to have been worked out under HMRC’s share identification rules already. Sell part of a holding you built up over several years and the allowable cost is a share of the pool, not the price of any particular batch. Buy the same shares back within 30 days and the sale is matched against that purchase instead, which is why selling and rebuying to use up the exempt amount does not work. The bed and ISA calculator does apply those rules: give it your purchases and a sale and it shows which shares were matched under which rule.
It deducts a whole annual exempt amount, every time it runs
The £3,000 exempt amount is one allowance for the whole tax year across every disposal you make, and this page has set all of it against the single disposal above. If you have other gains this year — another shareholding, a second property, crypto — part or all of the exemption is already spent, so the tax shown here is too low. Do not run the page once per disposal and add the answers: that deducts the exemption once per run.
It does not track your lifetime Business Asset Disposal Relief limit
Relief is capped at £1,000,000 of qualifying gains across your whole life, and this calculator has no record of what you have claimed before. Gains above the cap are charged at the ordinary capital gains rates instead of 18.00%, so if your earlier claims have used the cap up the tax shown here is too low. Keep your own running total.
Worked example
First, the part this calculator does not do
Ravi bought 1,000 shares in one company for £4,000.00, and two years later another 1,000 for £6,000.00. He now sells 1,000 of them for £9,000.00. He did not sell “the ones he bought at £6.00”, because for capital gains tax his whole holding is one asset — a s104 pool — with one average cost:
| Shares in the pool | 2,000 |
|---|---|
| Pooled cost | £10,000.00 |
| Average cost per share | £5.00 |
| Allowable cost of the 1,000 sold | £5,000.00 |
| Proceeds | £9,000.00 |
| Gain to enter above | £4,000.00 |
Had Ravi entered £3,000.00 — proceeds less what he paid for the second batch — the calculator would have answered £0.00 instead of £223.80, on Priya’s income below. The arithmetic would have been correct and the answer wrong, because the input was wrong. That is the whole reason this page says what it does not do, twice, above the figure.
Then, the part it does
Two people sell the same shareholding in 2026/27 and make the same £20,000 gain. They pay different amounts of capital gains tax, because the tax on a gain depends on the income sitting underneath it.
Priya earns £50,000.00. Her personal allowance leaves £37,430.00 of taxable income, and the basic rate for gains runs to £37,700 — so only £270.00 of basic-rate band is left. After the £3,000 exempt amount her chargeable gain is £17,000.00:
| Band | Gain in band | Rate | Tax |
|---|---|---|---|
| Basic rate | £270.00 | 18.00% | £48.60 |
| Higher rate | £16,730.00 | 24.00% | £4,015.20 |
| Capital gains tax | £4,063.80 |
Sam earns £20,000.00. Their taxable income is £7,430.00, so far more of the basic-rate band is free and the same gain is taxed mostly at the lower rate:
| Band | Gain in band | Rate | Tax |
|---|---|---|---|
| Basic rate | £17,000.00 | 18.00% | £3,060.00 |
| Capital gains tax | £3,060.00 |
Same shares, same gain, same year: £4,063.80 against £3,060.00. A calculator that asks whether you are a higher-rate taxpayer and applies one rate to the whole gain cannot produce either answer when the gain straddles the boundary, which it does for Priya.
Methodology and sources
The calculation, in order
- Start from the gain you entered. This page does not derive it. There is no same-day rule, no 30-day rule and no s104 pooling anywhere in this site’s engines, so the figure has to arrive already correct under HMRC’s share identification rules.
- Deduct the annual exempt amount, once. What is left is the chargeable gain. The exempt amount does not use up any of your basic-rate band, which is why the exempt slice of a gain never pushes the rest of it into the higher rate.
- Work out your taxable income: your income before tax, less the personal allowance the income tax engine says applies to it. Above £100,000 that allowance tapers, and the same engine that computes income tax handles it.
- Stack the chargeable gain on top of that taxable income. The part below the basic-rate ceiling is taxed at the basic rate for gains; the rest at the higher rate. One disposal can meet both.
- Gains qualifying for Business Asset Disposal Relief skip the stack entirely and are charged at a flat rate. The lifetime limit on that relief is not applied here.
Rates and allowances
| Figure | 2025/26 | 2026/27 |
|---|---|---|
| Annual exempt amount | £3,000 | £3,000 |
| Basic-rate band for gains (taxable income) | £37,700 | £37,700 |
| Shares and funds — basic / higher | 18.00% / 24.00% | 18.00% / 24.00% |
| Business Asset Disposal Relief | 14.00% | 18.00% |
| Relief lifetime limit (not applied by this page) | £1,000,000 | £1,000,000 |
| Personal allowance | £12,570 | £12,570 |
Where the figures come from
- Tax when you sell shares
- Shares and Capital Gains Tax (HS284) — the share identification rules
- Capital gains tax rates and annual tax-free allowances
- Capital gains tax: rates
- Business Asset Disposal Relief
- Income tax rates and allowances
The rates and allowances in the table above were verified against gov.uk on 12 August 2026. That check covers the published figures this page computes with. It does not verify any result the page produces, and it has not yet been signed off by a person — the verification recorded in the source repository is an automated one. Check anything that matters against gov.uk or with an accountant.
Every calculation runs in your browser. There is no application server and no database, so nothing you type is transmitted or stored. A share link is the exception: it carries your figures in the URL. More on what that means. Information, not advice. The long-form methodology for this calculator sets out the same arithmetic with every source and the full verification log.
Frequently asked questions
- Does this calculator work out the gain on my shares?
No, and that is the most important thing to know about it. You supply the gain and this page works out the tax on it. There is no share matching here — no same-day rule, no 30-day bed-and-breakfast rule and no s104 pooling — so if your holding was built up from more than one purchase, or you have bought the same shares again within 30 days of selling, the allowable cost is not what you paid for any particular batch and the gain must be worked out under HMRC’s share identification rules first. HMRC helpsheet HS284 sets them out, and the bed and ISA calculator on this site applies them to a list of purchases and a sale.
- What is the 30-day rule when selling shares?
If you buy shares of the same class in the same company within 30 days of selling, the sale is matched against that later purchase rather than against your pooled holding. It exists to stop "bed and breakfasting" — selling to use up the annual exempt amount and buying straight back — and it means the gain on that sale is calculated from the repurchase price, not the pool. This calculator does not apply the rule, so a figure you work out ignoring it will be wrong rather than approximate.
- How much can I gain on shares before I pay capital gains tax?
The annual exempt amount is £3,000 for 2026/27. It is one allowance for the whole tax year across every disposal you make — shares, property, crypto, anything chargeable — it is deducted before any tax is worked out, and any of it you do not use is lost rather than carried forward. This page deducts a full exempt amount against the single disposal you enter, so if you have other gains this year the tax it shows is too low.
- What rate of capital gains tax do I pay on shares?
Shares and funds are ordinary chargeable assets: 18.00% on the part of the chargeable gain that falls inside your remaining basic-rate band and 24.00% above it. The gain is stacked on top of your taxable income to decide which applies, so one disposal is often taxed at both rates. Residential property is charged at different rates and this page does not offer it.
- Do I pay capital gains tax on shares held in an ISA or a pension?
No. Gains on shares and funds inside a stocks and shares ISA or a pension are not chargeable, so there is nothing to enter here for them and they do not use up your annual exempt amount. Only disposals from a general investment account, or shares held directly, are within the scope of this calculator.
- Does selling shares push me into a higher income tax band?
No. A gain is stacked on top of your taxable income to decide which capital gains rate applies to it, but it is not income: it does not change your income tax, your personal allowance or your student loan repayments. What it can do is straddle the boundary, so part of one disposal is taxed at the basic rate for gains and the rest at the higher rate.
- I sold shares in my own company — is this the right calculator?
It can be. Choose the Business Asset Disposal Relief option if the disposal qualifies, and the gain is charged at a flat rate instead of being stacked against your income. What this page cannot do is track the lifetime limit on that relief: it is capped across every qualifying disposal you have ever made, this calculator has no record of your earlier claims, and gains beyond the cap are charged at the ordinary rates. If your claims have already used the cap up, the figure shown is too low.
- I sold shares and something else this year — can I run this page twice?
No, and adding two runs together would understate your tax, because each run deducts a full annual exempt amount. A year with more than one disposal needs the single exemption set against the gains taxed at the highest rate and the remainder stacked in one calculation, which this page does not do.