It is a tax on gains made on disposing of capital assets, such as shares, selling your business and property, whilst your main home is not normally subject to CGT. An annual exemption is basically the first £11,100 of gains you make in a year are exempt from tax.
Capital gains are taxed at an elevated rate of 20% (28% for residential property and carried interest) for gains where total taxable gains and income are atop the income tax basic rate band of£33,500. Under that, a 10% (18% for residential property and carried interest) rate is appertained.
But there are various reliefs that can lessen this. Most of the codification regarding capital gains tax is all about the exclusion and how to avoid it, so you often find there are ways around it or ways to lessen its footprint.