uk tax calculator capital gains

How UK capital gains tax is calculated

Capital Gains Tax is charged on the profit you make when you sell or dispose of certain assets. The key word is gain, not sale value. If you bought an asset for £100,000 and disposed of it for £140,000, your starting gain is £40,000 before adjustments.

In the UK, the amount of CGT you pay depends on:

• The type of asset (residential property usually has different rates).
• Your taxable income for the year.
• Your allowable costs and losses.
• Your Annual Exempt Amount (tax-free allowance).

1) Work out your net gain

Start from disposal proceeds, then subtract your purchase price and allowable costs. Allowable costs usually include buying/selling fees and qualifying capital improvements.

• Sale proceeds
• Minus purchase price
• Minus purchase and sale costs
• Minus improvement costs

2) Deduct losses

If you have allowable losses (from the same year or carried forward), you can usually offset these against gains before tax is calculated.

3) Apply the annual exempt amount

After losses, you generally apply your annual CGT allowance. In recent years this has reduced significantly compared with older tax years, so checking the right tax year matters.

4) Apply CGT rates based on income band and asset type

Your taxable gain can be split across lower and higher CGT rates, depending on how much basic rate band remains after your income is considered.

• Other assets: typically 10% (basic-rate portion) and 20% (higher-rate portion)
• Residential property: typically 18% (basic-rate portion) and 24%/28% depending on tax year
• BADR qualifying gains: usually 10% flat rate (subject to HMRC conditions and limits)

How to use this UK tax calculator for capital gains

Use these steps for a clean estimate:

1. Choose the correct tax year.
2. Select your asset type.
3. Enter disposal proceeds and costs accurately.
4. Include only allowable capital improvements, not normal maintenance.
5. Add available capital losses.
6. Enter your taxable income for the year before gains.

Once you click Calculate CGT, the tool shows your estimated taxable gain and estimated CGT due.

Example calculation

Suppose you sold a residential property (not your main home) for £320,000. You bought it for £240,000, spent £6,000 on buying/selling costs, and spent £14,000 on qualifying improvements. You also have £3,000 of allowable losses and taxable income of £45,000.

The calculator would:

• Calculate your net gain before reliefs.
• Subtract losses.
• Subtract annual exemption.
• Apply the residential CGT rates based on remaining basic rate band.

This gives you a quick estimate to help with cash planning before disposal.

Frequently asked questions

Do I pay CGT on every asset sale?

No. Some disposals are exempt, and some are covered by reliefs. Your annual exempt amount also reduces taxable gains.

Can I deduct renovation costs?

You can normally deduct qualifying capital improvements that add value or extend asset life. Routine repairs and maintenance are generally treated differently.

Do I need to report gains if tax due is zero?

Possibly. Reporting requirements can apply based on disposal totals, type of asset, and your circumstances.

Is residential property always taxed at higher rates?

Residential property usually has higher CGT rates than many other assets, but the exact rate still depends on your tax band and tax year.

Final note

If your numbers are significant, or if your situation includes multiple disposals, inherited assets, business shares, or relief claims, consider getting advice from a qualified UK tax professional. A short review can prevent expensive filing mistakes.