UK Capital Gains Tax Calculator
Estimate Capital Gains Tax on property, shares and other chargeable assets.
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UK Capital Gains Tax Calculator – Estimate Tax on Your Gains
Our UK Capital Gains Tax Calculator helps estimate the tax payable when you sell or dispose of assets such as shares, investments and residential property. Enter the sale price, purchase cost, allowable expenses, available capital losses and taxable income to calculate an estimated capital gains tax amount.
What Is Capital Gains Tax in the UK?
Capital Gains Tax (CGT) is a tax that may apply when you make a profit from selling or disposing of an asset that has increased in value. The taxable gain is generally based on the difference between the disposal proceeds and the allowable acquisition and disposal costs.
Depending on the asset and your circumstances, CGT may apply to:
- Shares and investment funds.
- Second homes and buy-to-let properties.
- Land and other chargeable assets.
- Business assets and certain valuable possessions.
- Other assets that are not covered by an exemption or relief.
Some disposals may qualify for exemptions or reliefs. Your actual tax liability depends on the asset, ownership, residence, available allowances and applicable tax rules.
How Does the UK Capital Gains Tax Calculator Work?
The calculator uses the information you enter to estimate your taxable gain and CGT.
- Select the tax year: Choose 2025/26 or 2026/27.
- Select the asset type: Choose shares, investments or other assets, or residential property.
- Enter the selling price: Add the amount received from disposing of the asset.
- Enter the purchase cost: Include the original acquisition cost.
- Add allowable expenses: Enter eligible buying, selling and improvement costs.
- Enter capital losses: Include available losses that may be used to offset gains.
- Enter taxable income: Provide taxable income before adding the capital gain.
- Select your ownership share: Choose the percentage of the gain attributable to you.
The calculator then displays estimated CGT, gain before losses, taxable gain, effective tax rate and estimated gain after tax.
How to Calculate Capital Gains Tax
The basic calculation starts by subtracting the original purchase cost and allowable expenses from the selling price.
For example, suppose you sell an investment for £50,000, originally purchased for £20,000, with £1,000 in allowable costs.
Selling price: £50,000
Purchase cost: £20,000
Allowable expenses: £1,000
Capital gain = £50,000 − £20,000 − £1,000 = £29,000
This is the gain before applying available capital losses and the annual exempt amount.
Allowable Costs When Calculating Capital Gains
Allowable costs can reduce the gain used in a CGT calculation. Depending on the asset and circumstances, these may include:
- Purchase costs directly associated with acquiring the asset.
- Qualifying legal and professional fees.
- Eligible costs associated with selling the asset.
- Qualifying capital improvement costs that add to or enhance the asset.
Routine repairs and maintenance generally cannot be treated as capital improvement costs for CGT purposes. Not every expense is allowable, so check the relevant HMRC rules before entering costs.
Capital Losses and Their Effect on CGT
Capital losses arise when an asset is disposed of for less than its allowable cost. Eligible losses may be used to reduce chargeable gains, subject to HMRC rules.
For example, if your gain is £29,000 and you have £4,000 of allowable losses available, the gain after losses would be £25,000 under this simplified illustration.
Losses may have specific reporting, ordering and carry-forward rules. The calculator does not model every loss treatment or the detailed ordering of multiple gains and losses.
Annual Capital Gains Tax Exempt Amount
The annual exempt amount is the amount of eligible capital gains an individual can realise in a tax year before CGT becomes payable, subject to the applicable rules.
Your calculator uses a fixed £3,000 annual exempt amount.
Gain after losses: £25,000
Annual exempt amount used by calculator: £3,000
Taxable gain = £22,000
The annual exempt amount is subject to tax-year rules and eligibility. Check the allowance applicable to the year of disposal.
Capital Gains Tax Rates Used by This Calculator
The calculator uses two CGT rates based on the unused portion of the basic-rate income tax band.
| Rate used | How the calculator applies it |
|---|---|
| 18% | Applied to the taxable gain that fits within the unused £37,700 basic-rate band. |
| 24% | Applied to the remaining taxable gain. |
The calculation uses the taxable income you enter to estimate how much of the basic-rate band remains available.
These are the simplified assumptions in the calculator. Actual CGT rates and thresholds can depend on the tax year, asset type and individual circumstances. The calculator currently does not distinguish residential property rates from other asset rates.
Example of a Capital Gains Tax Calculation
Consider the following example using the calculator's current assumptions:
Selling price: £50,000
Purchase cost: £20,000
Allowable expenses: £1,000
Gain before losses: £29,000
Capital losses: £0
Annual exempt amount: £3,000
Taxable gain: £26,000
Taxable income before gain: £30,000
Unused basic-rate band: £7,700
Gain taxed at 18%: £7,700 × 18% = £1,386
Gain taxed at 24%: £18,300 × 24% = £4,392
Estimated CGT under the stated assumptions: £5,778
This example demonstrates the calculation logic using the calculator's stated rates and thresholds. It is not a confirmation of the tax liability for an actual disposal.
Capital Gains Tax on Property and Shares
CGT treatment can differ depending on the asset being sold.
Capital Gains Tax on Shares
When you sell shares or investments for more than their allowable cost, you may make a chargeable gain. The calculation can involve purchase costs, selling fees, losses and applicable exemptions. Special rules may apply to share matching, employee shares and investment funds.
Capital Gains Tax on Property
CGT may apply when you sell a property that is not fully covered by Private Residence Relief. This can include certain second homes and buy-to-let properties. Your main home may qualify for relief if the relevant conditions are met.
Residential property disposals can also have specific reporting and payment deadlines. Check HMRC guidance for your circumstances.
Joint Ownership and Your Share of the Gain
If an asset is jointly owned, the gain attributable to each owner may depend on their beneficial ownership share and the relevant ownership arrangements.
Your calculator allows you to select 100%, 75%, 50% or 25% ownership. It applies that percentage to the sale proceeds, purchase cost, expenses and entered losses.
Actual ownership shares and the treatment of losses should be checked carefully. The calculator's percentage selection is a simplified estimate and may not reflect every joint ownership arrangement.
Benefits of Using an Online Capital Gains Tax Calculator
- Estimate potential CGT before selling an asset.
- Understand the effect of purchase and selling costs.
- Estimate how capital losses can reduce a gain.
- Include the annual exempt amount used by the calculator.
- Compare the estimated tax with the gain after tax.
- Explore different ownership percentages.
- Understand the potential tax impact of an asset disposal.
Important Limitations of This Calculator
This calculator is designed to provide a simplified estimate. It currently uses the same £3,000 annual exempt amount and 18%/24% CGT rates for both selectable tax years. The tax-year selection does not change its calculation.
The asset-type selection currently changes the explanatory note only; it does not apply separate residential property rates. The calculator also does not fully account for Private Residence Relief, Business Asset Disposal Relief, trusts, companies, special share rules, all loss carry-forward rules or other available exemptions and reliefs.
For these reasons, do not use the result as a final tax liability or as a substitute for an HMRC calculation or professional tax advice.
Frequently Asked Questions About UK Capital Gains Tax
What is Capital Gains Tax in the UK?
Capital Gains Tax is a tax that may be payable when you sell or dispose of an asset for more than its allowable cost. The amount depends on the gain, available losses, exemptions, reliefs and applicable tax rates.
How do I calculate capital gains?
Subtract the allowable purchase cost and eligible expenses from the selling price. The resulting gain may then be reduced by allowable capital losses and the annual exempt amount.
What is the annual CGT allowance?
The annual exempt amount is the amount of eligible gains an individual can realise before CGT becomes payable, subject to the applicable rules. This calculator currently uses £3,000.
Can capital losses reduce Capital Gains Tax?
Eligible capital losses can generally be used to reduce chargeable gains, subject to HMRC reporting, ordering and carry-forward rules.
Do I pay Capital Gains Tax when selling shares?
You may have to pay CGT if you sell shares for more than their allowable cost and the gain is not covered by an exemption or relief. The treatment depends on the type of shares and your circumstances.
Do I pay Capital Gains Tax when selling my main home?
You may qualify for Private Residence Relief when selling your only or main home if the relevant conditions are satisfied. The relief may reduce or eliminate the CGT due.
What is the difference between 18% and 24% CGT?
The rates used by this calculator are 18% and 24%. It applies 18% to the portion of taxable gain within the unused basic-rate band and 24% to the remaining gain. Actual rates depend on the applicable tax rules and asset type.
Does this calculator cover residential property CGT?
You can select residential property, but the current calculator does not apply a separate property rate calculation or calculate Private Residence Relief. Treat the result as a simplified estimate only.
Can I calculate CGT for jointly owned assets?
Yes. The calculator allows you to select an ownership percentage and applies it to the entered sale proceeds, cost, expenses and losses. Actual beneficial ownership and loss treatment may require a more detailed calculation.
Is this UK Capital Gains Tax Calculator free?
Yes. You can use the online calculator to estimate potential CGT based on the inputs and assumptions provided.
Capital Gains Tax Disclaimer
This UK Capital Gains Tax Calculator provides general estimates for information and educational purposes. It does not provide tax, legal or financial advice and does not calculate every exemption, relief or special tax rule. Tax rates and allowances can change. Check the latest HMRC guidance or consult a qualified tax professional before making decisions or submitting a tax return.