In general terms, a charge to capital gains tax arises when a chargeable person makes a chargeable disposal of a chargeable asset. The disposal may produce a profit (known as a gain) or a loss.
See Checklist ― calculation of capital gains and losses for issues to consider when reporting client gains and losses.
When considering the guidance below, note that the Chancellor announced at Autumn Budget 2017 that from April 2020 a payment on account of any CGT due on the disposal of residential property must be made within 30 days of completion. This had been expected to be effective from April 2019, but has been delayed by 12 months. Overview of tax legislation and rates (Nov 2017), para 2.34; Consultation: Payment window for residential property gains
Since 2016, it has been possible for taxpayers to voluntarily report a capital gain straight away via an online submission called the Real Time Transaction Tax Return. The tax can also be paid at the same time. However, this is aimed at taxpayers who do not submit Tax Returns annually and so can use the facility to avoid the need to complete a Tax Return to report the gain. This is discussed in more detail under ‘Reporting’ below.