Capital Gains Tax Calculator
Estimate CGT owed on the sale of shares or property.
What is the Capital Gains Tax Calculator?
A Capital Gains Tax (CGT) calculator estimates the tax owed when you sell (or "dispose of") an asset for more than you paid for it, such as shares or a second property. It works by subtracting your annual tax-free CGT allowance from the total gain to find the taxable gain, then applying the relevant CGT rate — which differs for residential property versus other assets like shares, and depends on whether you're a basic-rate or higher/additional-rate taxpayer. To calculate it manually, subtract the current annual exempt amount from your gain, then multiply the taxable portion by the applicable rate for your asset type and tax band, both of which are published and updated on gov.uk.
How it works
Capital Gains Tax is charged on the profit (gain) you make when you sell or dispose of an asset that's increased in value — not on the total sale price. Your annual tax-free allowance (the "annual exempt amount") is subtracted from your total gain first, and tax is then charged on the remainder at a rate that depends on the type of asset and your overall income tax band.
UK context
Residential property that isn't your main home (a second home or buy-to-let) is taxed at higher CGT rates than shares and most other assets, and higher/additional rate taxpayers pay a higher CGT rate than basic rate taxpayers on both. Your main home is normally exempt from CGT under Private Residence Relief, though this can be affected by periods of letting it out or having more than one residence — a genuinely complex area worth getting specific advice on if it applies to you.
Tips
- The CGT annual exempt amount has been reduced significantly in recent tax years — always check the current figure on gov.uk rather than assuming a previous year's allowance still applies.
- Losses on other asset disposals can sometimes be offset against gains in the same tax year, reducing your overall CGT bill — this needs to be reported even if no tax is due.
- CGT on UK residential property (that isn't exempt) generally needs to be reported and paid within a set window after completion, separately from your annual Self Assessment return.
Frequently asked questions
How is Capital Gains Tax calculated?
Subtract your tax-free annual exempt amount from your total gain, then apply the relevant CGT rate (which depends on asset type and your tax band) to the remaining taxable gain.
Why does property have a different CGT rate from shares?
UK tax policy applies higher CGT rates to gains on residential property that isn't your main home compared with gains on shares and most other assets — this is a deliberate distinction set by the government, not an error or coincidence.
Do I pay CGT when I sell my main home?
Usually not — your main home is normally exempt under Private Residence Relief. This can be affected by factors like periods of letting the property out or owning more than one residence, so check the specific rules if your situation isn't straightforward.
Has the CGT tax-free allowance changed recently?
Yes — the annual exempt amount has been reduced substantially in recent tax years, so it's particularly important to check the current gov.uk figure rather than relying on an older remembered number.
A quick note
CGT rates and the annual exempt amount change and depend on your total taxable income for the year — this is an illustrative estimate. Always check current gov.uk rates and consider professional advice for significant disposals.