Disclaimer

This tool runs general calculations to help you understand your likely Capital Gains Tax position. It gives you an estimate to work from and a clear breakdown to discuss with a professional. For advice on your own situation, or to file your return, speak to a qualified accountant or tax adviser.

The results depend entirely on the data you provide. Incomplete or modified CSV exports, missing acquisition history, corporate actions, accumulation-unit income, or transactions in formats we don't yet support can all affect the figures. You are responsible for checking that your inputs are complete and that the output is correct for your circumstances.

The current version supports shares and ETFs from Trading 212 and Interactive Brokers, for a single tax year. It does not handle cryptocurrency, brought-forward or carried-forward losses, or every corporate action.

We apply HMRC's share-matching rules in their required order: the same-day rule, the 30-day “bed & breakfast” rule, and then the Section 104 pool (HMRC reference CG51560). Gains above the Annual Exempt Amount are taxed at 18% within your remaining basic-rate band and 24% above it, based on the income figure you enter.

To the fullest extent permitted by law, we accept no liability for any loss or damage arising from your use of, or reliance on, this tool or its output. Use it as a helpful estimate and a starting point for a conversation with a professional, not the final word on your tax.