Hi Mike Cowlishaw,
The disposal of shares for more than they were acquired for, results in a capital gain.
The new method of reporting those gains is by declaring the gain online at:
Report and pay your Capital Gains Tax
This should be done before 31 December after the tax year has ended.
If the ‘real time’ Capital Gains Tax service is not used to report the gains before 31 December, then the gains must be reported in a Self Assessment tax return.
Thank you.