Anyone who has tried working through the Inland Revenue matching rules for share trades will know that the process can quickly become very complicated for even a modest number of trades. The 30 day rule especially can cause unexpected gains/losses. The purpose of this site is to help UK tax payers to calculate, and to keep track of, their capital gain (or loss) based on their share trades. This is important for effective tax planning and can potentially save you a significant amount on your tax bill.

To use the capital gains calculator simply store your trades in a spreadsheet, or a simple text editor like Notepad, in a simple format. If you use an online stockbroker then check the conversion utilities for a suitable converter. Also note that transfers to spouse are supported. See the FAQ for frequently asked questions.

To view a bar chart showing the breakdown per stock of gains/losses over a tax year click the View Chart button.

This calculator is updated every year and is fully up to date for all tax years up to 2025-2026.

Useful Links:

• Shares and Capital Gains Tax
• Rules For Selling Your Shares
• Shares of negligible value
• Capital Gains Rates and Allowances
• Income Tax Rates and Bands
• What to do if you made a loss
• Capital Gains Tax Discussion Forum

Capital Gains Info:

	2024-2025	2025-2026
Exemption	3000	3000
Basic Rate	10 or 18%	18%
Higher Rate	20 or 24%	24%

Last updated July 2025