Capital Gains Tax Calculator
Estimate UK Capital Gains Tax when you sell a buy-to-let, second home, shares, funds or a qualifying business asset. It works out the gain, deducts costs and losses, applies the annual exempt amount, then stacks the taxable gain on top of your taxable income.
Estimate Capital Gains Tax
Enter one disposal. If you have several disposals in the same tax year, combine gains and losses before relying on the result.
Sale and cost details
Capital improvements can reduce the gain; normal repairs already deducted from income should not be counted again.
Allowances, income and shares
GOV.UK uses taxable income after Personal Allowance and other Income Tax reliefs when stacking gains into the basic rate band.
GBP 3,000 for individuals, unless some or all of the annual exempt amount has already been used on another gain.
Annual exemption
GBP 3,000
The individual CGT tax-free amount before taxable gains are charged.
Main CGT rates
18% / 24%
Gains are stacked on top of taxable income to decide the split.
Property deadline
60 days
Most UK residential property gains with tax due must be reported quickly.
CGT is a gain calculation, not a sale-price tax
Capital Gains Tax is based on the profit you make when you dispose of an asset, not the full amount you sell it for. For a property, that usually means sale proceeds minus the original purchase price, buying and selling costs, and qualifying improvement costs. For shares or funds, it means comparing the disposal value with the allowable acquisition cost and dealing costs.
The next step is where people often go wrong. You do not simply multiply the whole gain by one rate. GOV.UK says you deduct losses and the annual exempt amount, then add the taxable gain on top of taxable income. Any part inside the unused basic rate band is charged at 18%, and the rest is charged at 24% for current individual rates.
If your disposal qualifies for Business Asset Disposal Relief, the calculation is different. Qualifying gains are charged at the BADR rate up to the lifetime limit: 14% in 2025/26 and 18% from 2026/27.
| Asset | What to watch |
|---|---|
| Buy-to-let / second home | 60-day reporting, improvement costs, PRR edge cases. |
| Shares and funds | Pooling, ISA/pension exemptions and same-day/30-day rules are not modelled. |
| Business disposal | BADR conditions and lifetime limit must be checked carefully. |
| Main home | Private Residence Relief can remove or reduce CGT, but this page does not calculate it. |
| Jointly owned assets | Each owner normally calculates their own share, allowance, income and losses. |
How this CGT calculator works
Inputs used
- Tax year and asset type.
- Sale proceeds, original cost, buying/selling costs and capital improvements.
- Your ownership share.
- Taxable income after Personal Allowance and other Income Tax reliefs.
- Allowable capital losses and annual exempt amount used on this disposal.
- Business Asset Disposal Relief lifetime limit already used, where relevant.
Calculation method
- Calculate the gross gain: sale proceeds minus purchase cost and allowable costs.
- Apply the ownership share to the gain, costs and proceeds.
- Deduct allowable losses and the annual exempt amount.
- For normal gains, stack taxable gains on top of taxable income and split between the unused basic rate band and higher-rate slice.
- For BADR, apply the qualifying relief rate up to the remaining lifetime limit and normal rates to any excess.
- Show CGT due, effective rate, basic-rate slice, higher-rate slice and reporting notes.
Assumptions
- The annual exempt amount is GBP 3,000 for individuals unless you enter a lower amount because it has been used elsewhere.
- Taxable income means income after Personal Allowance and Income Tax reliefs, matching the GOV.UK CGT examples.
- Current individual CGT rates are 18% in the unused basic rate band and 24% above it.
- BADR is assumed to be valid only if you select that route; this calculator does not test every condition.
- Costs entered are assumed to be allowable capital costs, not normal repairs or revenue expenses.
What this does not cover
- It does not calculate Private Residence Relief, letting relief, divorce/separation no-gain-no-loss rules, share pooling, same-day or 30-day share matching, EIS/SEIS reliefs, Gift Hold-Over Relief, Rollover Relief, or non-resident property rebasing.
- It does not calculate landlord rental income tax. Use the UK Landlord Tax Calculator.
- It does not calculate rental yield. Use the Property Rental Yield Calculator.
- It does not calculate SDLT, Wales LTT or Scotland LBTT on purchase. Use the Stamp Duty Calculator, Wales LTT Calculator or Scotland LBTT Calculator.
Worked example: selling a buy-to-let
Say you sell a rental flat for GBP 350,000. You bought it for GBP 240,000, spent GBP 8,000 on buying and selling costs, and made GBP 12,000 of capital improvements. The raw gain is GBP 90,000.
After the GBP 3,000 annual exempt amount, the taxable gain is GBP 87,000 if there are no capital losses. If your taxable income is GBP 30,000, there is GBP 7,700 of basic rate band left, so that part of the gain is charged at 18% and the rest at 24%.
Because this is UK residential property, a gain with tax due normally needs reporting and paying through the CGT on UK property service within 60 days of completion. Do not leave that bit for the January tax return.
What counts as a cost?
Typical allowable capital costs include the original purchase price, Stamp Duty or devolved property tax paid on purchase, legal fees, estate-agent fees and improvement costs that add value to the asset. A new extension is more likely to be capital than replacing a broken fitting.
Normal repairs usually belong in the landlord income tax world, not the CGT base cost. If you already deducted a cost from rental income, be careful about also treating it as a CGT improvement.
Shares and funds can be more fiddly than a single purchase price. Pooling, dividend reinvestment, accumulation units and same-day or 30-day matching can alter the allowable cost, so keep broker statements.
Common CGT mistakes
Using gross income instead of taxable income
GOV.UK stacks gains on top of taxable income after Personal Allowance and reliefs, not simply salary before deductions.
Forgetting the 60-day property deadline
UK residential property disposals with CGT due usually need reporting and payment within 60 days of completion.
Treating repairs as improvements
Capital improvements can reduce a gain, but ordinary repairs may not be allowable CGT base costs.
Assuming BADR automatically applies
Business Asset Disposal Relief has strict conditions and a lifetime limit. Select it only where the disposal qualifies.
Capital Gains Tax FAQs
What costs can I deduct for CGT?
Do I pay CGT when I sell my home?
How do losses work?
What if I own the asset jointly?
Official sources
Last verified: May 9 2026. Calculations are estimates based on the published rules and assumptions shown on this page.
- GOV.UK Capital Gains Tax overview - what CGT applies to, losses, reporting and record-keeping context
- GOV.UK Capital Gains Tax allowances - GBP 3,000 annual exempt amount and loss/relief context
- GOV.UK Capital Gains Tax rates - 18% and 24% rates, income-band stacking and allowance allocation
- HMRC CGT rates and allowances guidance - 2025/26 and 2026/27 rates, trustees, personal representatives and relief rates
- GOV.UK report and pay CGT on UK property - 60-day UK residential property reporting and payment deadline
- GOV.UK Business Asset Disposal Relief - 14% rate for 2025/26, 18% rate from 2026/27 and lifetime limit context