For UK property disposals which are not your main home, capital gains tax (CGT) will be due on gains which exceed the annual exempt amount (AEA).
From 6 April 2020, if you’re a UK resident, you’ll have to report and pay any CGT due within 30 days of the completion date. You do not have to report the gain if there is no tax due. If you’re a non-resident, you must report all sales or disposals of UK property, even if you have no tax to pay or have made a loss.
Currently, you have to use HMRC’s online services to report and pay CGT due on property disposals:
If you’re an agent, you’ll need to use your client’s Capital Gains Tax on UK Property account after requesting authorisation via your Agent Services Account.
See our knowledgebase article for capital gains tax rates and allowances