About this calculator
The Capital Gains Tax Calculator estimates UK CGT on shares, stocks, property, crypto, business assets, and other disposals. It is for investors, landlords, employees with share options, crypto holders, and anyone checking whether a sale may create a taxable gain. The calculator helps separate sale proceeds, allowable costs, annual exempt amount, losses, taxable gain, and the CGT rate that may apply. It is especially useful for GSC queries around shares tax, stock taxes, CGT on shares, and capital gains tax calculator UK.
UK CGT calculation method
The basic calculation is sale proceeds minus allowable acquisition cost and disposal costs. Available losses and the annual exempt amount reduce the chargeable gain. The remaining taxable gain is then taxed at the relevant CGT rate. GOV.UK lists the annual exempt amount as GBP 3,000 for individuals and personal representatives for 2025/26, and the main rates depend on asset type and taxable income position.
- gain = sale proceeds - purchase cost - allowable costs
- chargeable gain = gain - available losses - annual exempt amount
- CGT due = chargeable gain x applicable CGT rate
- net proceeds after tax = sale proceeds - CGT due - selling costs
How to use the CGT calculator
- Choose the asset type, such as shares, property, crypto, or other assets.
- Enter the sale proceeds before tax.
- Enter the purchase cost or pooled acquisition cost.
- Add allowable buying and selling costs where relevant.
- Enter unused capital losses that can be set against the gain.
- Apply the annual exempt amount only once across gains in the tax year.
- Review taxable gain, estimated CGT, and the amount left after tax.
Worked examples
Shares gain example
Input: Shares sold for GBP 25,000, original cost GBP 14,000, selling costs GBP 100
Calculation: GBP 25,000 - GBP 14,000 - GBP 100 = GBP 10,900 gain before allowance
Result: After a GBP 3,000 annual exempt amount, the taxable gain is GBP 7,900 before applying the CGT rate.
Loss offset example
Input: Gain of GBP 12,000 and allowable capital loss of GBP 4,000
Calculation: GBP 12,000 - GBP 4,000 - GBP 3,000 annual exempt amount
Result: The taxable gain is GBP 5,000.
Property gain planning
Input: Property gain with legal fees, estate agent fees, and improvement costs
Calculation: Allowable costs reduce the gain if they qualify and records are kept.
Result: The calculator shows the taxable gain after costs, but property reporting deadlines should be checked separately.
Shares, stocks, and pooled costs
Share CGT often depends on the pooled cost of holdings rather than the price of one individual share certificate. If you buy the same class of shares in the same company several times, the cost may need to be averaged under share matching and pooling rules. The calculator is useful for estimating the final taxable gain, but the input cost should be prepared carefully.
What can change the CGT result
| Factor | Effect on calculation | Planning note |
|---|---|---|
| Annual exempt amount | Reduces total gains for the tax year | Do not apply it separately to every asset |
| Capital losses | Can reduce chargeable gains | Losses usually need records and may need reporting |
| Income level | Can affect the CGT rate band | Estimate taxable income before choosing a rate |
| Asset type | Different rates can apply | Residential property and carried interest can differ from other assets |
| Allowable costs | Reduce the gain if eligible | Keep contract notes, invoices, and completion statements |
Records to keep
- Shares and funds
- Keep contract notes, dividend reinvestment records, corporate action details, and platform transaction history.
- Property
- Keep completion statements, legal bills, estate agent invoices, and evidence for qualifying improvement costs.
- Crypto assets
- Keep exchange exports, wallet transactions, fees, transfers, and records of disposals or swaps.
Common CGT mistakes
- Applying the annual exempt amount separately to each sale instead of across the tax year.
- Ignoring share pooling and same-day or 30-day matching rules.
- Forgetting transaction costs that may be allowable.
- Treating ISA disposals as taxable when gains inside ISAs are usually tax-free.
- Assuming no tax is due because no cash was withdrawn from an investment platform or exchange.
Tax information disclaimer
This calculator is for general information only and is not tax advice. CGT rules, rates, reliefs, reporting deadlines, residence status, and asset-specific rules can change. Check current HMRC guidance or speak to a qualified adviser before filing or making a disposal decision.
- It does not calculate every relief or share matching case.
- It does not file a tax return or property CGT return.
- It assumes the entered costs, losses, and income position are accurate.
Frequently asked questions
How is Capital Gains Tax calculated?
Start with sale proceeds, subtract allowable costs and purchase cost, deduct available losses and the annual exempt amount, then apply the relevant CGT rate.
What is the CGT annual exempt amount?
For 2025/26 GOV.UK lists the individual annual exempt amount as GBP 3,000. Check current HMRC guidance because allowances can change.
Do I pay CGT on shares?
You may pay CGT on shares held outside tax-free wrappers if your total taxable gains exceed available losses and the annual exempt amount.
Are ISA gains taxable?
Gains inside an ISA are generally free from UK CGT, but investments outside ISAs may be taxable.
Can capital losses reduce CGT?
Allowable capital losses can usually reduce chargeable gains, but records and reporting rules matter.
Related calculators
- Business Capital Gains Tax Calculator
- Income Tax Calculator
- Crypto CGT Calculator
- Inheritance Tax Calculator