Section 517I | Calculation of surplus on a disposal of land
From legislation.gov.uk
For the purposes of this Part, the profit or gain (if any) from a disposal of any property is to be calculated according to the principles applicable for calculating the profits of a trade under Part 2 of ITTOIA 2005, subject to any modifications that may be appropriate (and for this purpose the same rules are to apply in calculating losses from a disposal as apply in calculating profits).