How UK Capital Gains Tax is calculated (2026/27)

The working order is: take what you sold it for (or market value if you gave it away), subtract allowable costs, and only then think about tax. Allowable costs usually mean what you paid for the asset, plus certain buying and selling fees, plus qualifying improvement costs. The sale price itself is not the tax base. A £320,000 second home that cost £300,000 is a £20,000 gain, not a £320,000 gain.

GOV.UK’s own worked examples start from a figure they already call “taxable gains”. Our calculator reconstructs that as proceeds minus costs so you can type the two numbers you actually have. The £12,600 GOV.UK example is entered here as £112,600 proceeds and £100,000 costs. Change either box and the gain moves. A loss on disposal is not taxed; it can often be set against other gains instead.

You only pay Capital Gains Tax if overall gains for the tax year, after losses and reliefs, sit above the annual exempt amount. For most individuals in 2026/27 that allowance is £3,000. Most trustees have £1,500 — not modelled here. Unused allowance cannot be carried forward to next year. Unused losses often can.

Worked example: proceeds £50,000, costs £48,000, taxable income £20,000. Gain £2,000. The whole £2,000 fits inside the £3,000 allowance. Chargeable gain £0. Estimated CGT £0. Crossing the allowance by a pound does not tax the first £3,000.

People often say “I pay 24% CGT” as if it were a single stamp on every pound of profit. For individuals it is a split. GOV.UK’s method: work out taxable income (income minus Personal Allowance and other Income Tax reliefs). Work out the chargeable gain after the annual exempt amount. Add those two figures. The part of the gain that still fits inside the rUK basic-rate band of £37,700 is charged at 18%. Anything above is charged at 24%. If you are already a higher or additional-rate taxpayer, unused band is usually £0 and the whole chargeable gain is at 24%.

Worked example — GOV.UK example 1, on or after 6 April 2026. Taxable income £20,000. Taxable gains £12,600. Deduct the £3,000 allowance, leaving £9,600. Add that to income: £29,600, which is still below £37,700. The whole chargeable gain is at 18%. £9,600 × 18% = £1,728. Unused basic-rate band was £17,700 (£37,700 − £20,000), so the £9,600 fitted with room to spare.

A larger gain uses up the leftover basic-rate band and then spills into 24%. That is GOV.UK’s second example, and it is why two people with the same profit can pay different bills: the leftover band depends on their taxable income, not on the asset.

Worked example — GOV.UK example 2. Taxable income £20,000. Taxable gains £52,600. After the £3,000 allowance the chargeable gain is £49,600. Unused basic-rate band is still £17,700, charged at 18% → £3,186. The remaining £31,900 is at 24% → £7,656. Total CGT £10,842. From 6 April 2026 those same 18% and 24% rates apply to residential property and to other chargeable assets. They used to differ. The calculator still asks which kind of asset it is, because a UK property disposal with tax to pay has a different reporting clock — not because the 2026/27 rate table splits.

The income box is the same “taxable income” GOV.UK uses in those examples, not your headline salary. A salary of £32,570 with a full Personal Allowance of £12,570 and no other reliefs is £20,000 of taxable income. That is why GOV.UK’s first example and our default button both use £20,000. Entering £32,570 in the income box would shrink the unused basic-rate band and overstate the tax. Pension contributions and other Income Tax reliefs can change the leftover band; enter the figure after those reliefs if you know it.

Scottish taxpayers still split CGT using rUK Income Tax bands, not the Scottish starter, basic, intermediate, higher or top rates. There is no Scotland toggle on this calculator. Trustees and personal representatives generally pay 24% on the whole chargeable gain — also not modelled as a separate engine.

Current-year allowable losses reduce the gain first. Then the annual exempt amount is applied to what is left. That order matters: a loss can pull a gain back under the £3,000 line, or leave a smaller chargeable slice at 18% or 24%.

Worked example: proceeds £115,000, costs £100,000, allowable losses £5,000, taxable income £20,000. Gain before losses £15,000. After losses £10,000. After the £3,000 allowance, chargeable £7,000. Unused basic-rate band is £17,700, so all of it is at 18%. Estimated CGT £1,260. Unused annual exempt amount cannot be carried forward. Unused losses often can — this tool does not file a loss claim.

If taxable income already fills the £37,700 basic-rate band, unused band is £0 and the chargeable gain is all at 24%. Worked example: a £20,000 property gain (proceeds £320,000, costs £300,000) with £40,000 of taxable income. After the £3,000 allowance the chargeable gain is £17,000. 24% × £17,000 = £4,080. The same £20,000 gain on GOV.UK example 1’s £20,000 income would have leftover band and a lower bill — income, not just the profit, sets the rate.

UK residential property with Capital Gains Tax to pay is usually reported and paid within 60 days of completion, separately from the Self Assessment return. That clock is not a calendar on this page. Your only or main home is a different story: Private Residence Relief often means no CGT at all, which is why this is the wrong calculator for selling the house you live in. Confirm the 60-day rules on GOV.UK when a UK property is in play.

Private Residence Relief, lettings relief, the £6,000 chattels limit, crypto same-day and 30-day pooling, foreign currency, holdover, transfers between spouses or civil partners, a spouse’s unused annual exempt amount, and CGT on trusts are all outside this model. From 6 April 2026, Business Asset Disposal Relief and Investors’ Relief charge qualifying gains at 18% — a different rate table, not a toggle here. Trustees and personal representatives generally pay 24%. Carried interest is charged to Income Tax and National Insurance from 6 April 2026, not as CGT on this page.

A result of £0 is not the same as “no paperwork”. You may still need to report the disposal. If GOV.UK, a 60-day property return or a tax adviser disagrees with a web calculator, those documents win.