The basic principle is the same for individuals and companies - the tax applies only on the disposal of a capital asset, and the amount of the gain is calculated as the difference between the disposal proceeds and the "base cost", being the original purchase price plus allowable related expenditure. However, from 6 April 2008, the rate and reliefs applicable to the chargeable gain differ between individuals and companies. Companies apply "indexation relief" to the base cost, increasing it in accordance with the Retail Prices Index so that (broadly speaking) the gain is calculated on a post-inflation basis (with different rules apply for gains accrued prior to March 1982).