Tax law says that an expense is allowable for tax if it is incurred ‘wholly and exclusively for the purposes of the trade’. If an expense is incurred for more than one purpose, i.e. business as well as personal use, a deduction for any identifiable proportion of the expense which is incurred ‘wholly and exclusively for the purposes of the trade’ is allowable. We have set out some of the types of expenditure that may be allowable.