UK Capital Gains Tax Calculator
Calculate UK Capital Gains Tax on shares, property, or other assets. Enter your total realised gains and your other taxable income — the calculator subtracts the £3,000 annual exempt amount, then taxes the balance at 18% or 24% depending on whether your income fills the basic-rate band.
How is this calculated?
Each tax year you have a £3,000 annual exempt amount (frozen since April 2024). Gains above that are added to your taxable income to determine the rate: any portion that fits within the unused basic-rate band (£37,700 above the £12,570 Personal Allowance) is taxed at 18%; gains above that are taxed at 24%. Both residential and non-residential rates have converged to 18%/24% post the 30 October 2024 Budget. Business Asset Disposal Relief (10% / 14% / 18% on first £1m of qualifying business gains) is not modelled here.
Frequently Asked Questions
Do I pay CGT if my gains are under £3,000?
No — the first £3,000 of total gains in a tax year is the annual exempt amount. Below that, no CGT is due. You may still need to report gains if you sell a UK residential property, even when no tax is owed.
When do I pay UK CGT?
Most CGT is paid via Self Assessment — by 31 January after the end of the tax year. UK residential property disposals must be reported and paid within 60 days of completion using HMRC's online service.
What about losses?
Capital losses in the same tax year offset capital gains pound-for-pound. Unused losses can be carried forward indefinitely (provided they're reported within 4 years of the tax year). This calculator handles a single net gain figure — net your losses before entering.
Are ISA gains taxed?
No — gains inside an ISA or pension wrapper are completely free of CGT. The £3,000 annual exempt amount only matters for gains in unwrapped (general investment account) holdings.
Last updated: May 2026 · Rates sourced from HMRC