Capital gains tax (CGT) may be due on a sale of UK residential property.
The gain subject to tax is the difference between the cost of acquiring the property, plus any allowable costs of sale and acquisition, and the sale proceeds. Costs of improving the property during the period of ownership, if reflected in the state of the property at the date of sale, can also be deducted.
Private residence relief (sometimes referred to as main residence relief), the capital gains tax (CGT) annual exempt amount and any current year or brought forward capital losses may be available to reduce the gain. Any taxable gain is then subject to capital gains tax (CGT) at a rate of either 18% or 28%, depending on the individual’s overall tax position.
CGT 60-day reporting
When UK-resident individuals sell a UK residential property at a gain they may need to make a payment of tax within 60 days of completion. A special return may also need to be filed by the same date, irrespective of whether or not the seller is already in self-assessment.  Prior to 27 October 2021, the reporting window and payment date were only 30 days from completion.
Similar rules exist for non-UK residents disposing of any UK property, although non-residents generally need to file a return regardless of whether or not there is tax to pay.
Where the taxpayer is in self-assessment, the disposal will also need to be reported on the relevant tax return.