The SA108 form is used to report capital gains and losses from the sale or disposal of assets, such as property, shares, and artwork. The form is used to calculate the total capital gain or loss, which is then used to calculate the CGT liability.

You can fill out the form and submit it online through the Government Gateway, or you can file a paper tax return. It's important to keep records of all the transactions, costs and expenses related to the assets for at least 22 months after the end of the tax year in which the disposal took place, in case of any queries from HMRC.