In principle, all legitimate business expenses which are revenue in nature, incurred to derive taxable income will be deductible, although the timing of the deduction may vary for different types of expenses and the accounting method applied. For capital assets, expenditure would generally be recognized by way of depreciation or amortization deductions over the economic life of the asset or benefit.
Expenditures that have a dual purposes, such as expenses incurred for both personal and business purposes, will need to be apportioned with the relevant portion of the expenditure treated as incurred wholly and exclusively for the purpose of the taxable person’s business.