Calculator

Capital Gains Tax Calculator

See how your gains, losses, annual allowance and income combine to determine ordinary Capital Gains Tax.

Estimate annual tax on supported ordinary gains. Use your own share after the correct cost basis and reliefs. Your figures stay in this page.

Your gains and reporting situation

How would you like to enter the gain?

Capital Gains Tax situation

Total prepared gains in this tax year (£)

Your own share after applicable costs and reliefs, before annual losses and the £3,000 allowance. Include all supported disposals once.

Current-year allowable capital losses (£)

Enter losses as a positive amount. Do not repeat a loss calculated by the simple helper.

Unused reported losses from earlier tax years (£)

CGT already paid for this tax year (£)

Does this include a UK residential property disposal?

Are you registered for Self Assessment?

Tax year and annual income

Tax year

Income Tax region

Other annual taxable pay, pension or profit (£)

Use the taxable amount before the Personal Allowance. Include taxable benefits; do not use take-home pay.

Taxable savings interest (£)

Include interest within your savings allowance. Leave out ISA interest.

Ordinary dividends outside ISAs (£)

Include the £500 dividend allowance. Leave out property income distributions and foreign-tax-credit cases.

Eligible gross relief-at-source pension (£)

Include tax relief added by the provider: £80 paid is normally £100 gross. Do not repeat deductions already removed from taxable pay.

Eligible gross Gift Aid donations (£)

Include the basic-rate gross-up: a £80 donation is normally £100 gross. Check that enough UK tax covers the charity’s reclaim.

Pension and Gift Aid entries must already qualify for relief. This estimate does not check pension annual allowances, foreign income, property finance costs or specialist reliefs.

One annual allowance, across your disposals

The individual annual exempt amount is £3,000 in 2026/27. Ordinary gains above it are charged at 18% within your unused UK basic-rate band and 24% above that. The calculation uses current losses first and preserves earlier losses once gains reach the annual allowance.

At £20,000 taxable income and £12,600 gains before the annual allowance, CGT is £1,728 with no losses or special reliefs. £32,570 ordinary income with the standard Personal Allowance gives that £20,000 taxable-income example.

The simple helper covers a normal purchase and disposal with unchanged ownership. Repeated share purchases, 30-day matching, crypto transaction matching, employee shares, gifts, inherited assets, home relief, business reliefs and residence exceptions need their own calculation. You can enter a prepared gain after those rules have been applied; this tool does not establish eligibility for them.

Understand the calculation · Use capital losses correctly · Check the property deadline · Calculate dividend tax

Sources checked 12 November 2026: HMRC CGT rates and examples, loss rules and reporting and payment. Annual planning estimate; it is not a tax-return submission or a provisional property payment calculation.