capital gains tax uk calculator

How this capital gains tax UK calculator works

This calculator gives you a practical estimate of UK Capital Gains Tax (CGT) for individuals. It starts with your disposal gain (sale proceeds minus purchase price and allowable costs), then applies losses, reliefs, and the annual exempt amount to reach a taxable gain. Finally, it estimates tax at lower and higher CGT rates based on your taxable income and available basic rate band.

It is designed for quick planning, not formal tax filing. Real calculations can become more complex if you have multiple disposals, mixed asset types, trusts, non-residence issues, or reliefs with specific conditions.

What counts as an allowable cost?

Allowable costs generally reduce your chargeable gain. Typical examples include:

• Purchase costs directly linked to acquisition (e.g., legal fees, stamp duty on property).
• Selling costs directly linked to disposal (e.g., estate agent fees, solicitor fees, transfer costs).
• Capital improvement costs that add value or extend useful life.

Routine repairs and maintenance are usually treated differently and may not qualify as capital improvements for CGT purposes.

UK CGT rates used in this estimate

Standard assets (shares, funds, many investments)

• Lower rate portion: 10%
• Higher rate portion: 20%

Residential property (where CGT applies)

• Lower rate portion: 18%
• Higher rate portion: 24%

The calculator splits your taxable gain between lower and higher rate portions using your taxable income and your remaining basic rate band. If your income already exceeds the basic band, your gain is generally taxed at the higher CGT rate.

Step-by-step example

Suppose you sell an investment property for £300,000, bought for £220,000, with £5,000 buying costs, £6,000 selling costs, £9,000 improvement costs, £4,000 losses, taxable income of £30,000, and annual exempt amount of £3,000:

• Gross gain = £300,000 - (£220,000 + £5,000 + £6,000 + £9,000) = £60,000
• After losses = £60,000 - £4,000 = £56,000
• After annual exempt amount = £56,000 - £3,000 = £53,000 taxable gain
• If unused basic band is £7,700, that part is taxed at 18% and the rest at 24%

The tool automates this breakdown for you instantly.

Important UK points to remember

1) Annual Exempt Amount

Most individuals have an annual exempt amount that can reduce gains before CGT is charged. If your net gains are below this amount, CGT may be zero.

2) Capital losses can be valuable

Unused allowable losses can often be carried forward (subject to HMRC rules) and used against future gains. Keeping records is essential.

3) Property reporting deadlines

For UK residential property disposals where tax is due, reporting and payment deadlines can be much shorter than the normal Self Assessment cycle. Always check current HMRC requirements.

4) Reliefs may significantly change tax

Certain disposals may qualify for reliefs that lower tax or defer gains. Eligibility rules are specific and can materially affect outcomes.

Frequently asked questions

Is this calculator suitable for crypto and shares?

Yes, in many straightforward cases. Select the standard asset type and enter your disposal figures. If you have many transactions, pooled cost rules and recordkeeping can make calculations more complex.

Does this include every relief automatically?

No. The “Other Reliefs” field is a generic manual adjustment for planning estimates. You should confirm eligibility and amounts before filing.

Can I use this for company tax?

No. This calculator is for personal UK CGT estimation, not corporate tax computations.

Final thought

A good CGT estimate helps you make better decisions before you sell. Use this calculator early, test different scenarios, and keep clear records of costs and losses. For formal tax returns or complex cases, seek professional advice.

Disclaimer: This page is educational and not tax advice. Tax rules and rates can change; always verify with current HMRC guidance or a qualified adviser.