How do you work out gain/loss on accumulated shares?

[runarownd]

If you accumulate shares in a company over time, e.g. every month for 12 months, then later decide to sell some, how do you work out the gain/loss? i.e. how do you know whether you are selling the shares you bought in month 1 or month 12? Does each share have a serial number so it can be individually identified?

You have to work out the average. Also see note about buying the same shares you sold within 30 days.

https://www.gov.uk/tax-sell-shares/same-company