Income tax expense or benefit comprises the sum of current and deferred tax.
The current tax payable or receivable is based on taxable profit for the year. Taxable profit or loss differs from profit or loss as reported in the statement of comprehensive income as it excludes items of income or expense that are taxable or deductible in other years in the determination of taxable profit or loss (temporary differences). It further excludes items that are never taxable nor deductible (non-temporary differences). The group's liability for tax is calculated using tax rates that have been enacted or substantively enacted at the reporting date.
Deferred tax is provided using the balance sheet method on all temporary differences between the carrying amounts for financial reporting purposes and the amounts used for tax purposes.
A deferred tax asset is recognised to the extent that it is probable that future taxable profits will be available against which the associated unused tax losses and deductible temporary differences can be utilised. The carrying amount of deferred tax assets is reviewed at each reporting date and reduced to the extent that it is no longer probable that sufficient future taxable profits will be available to allow all or part of the asset to be recovered.
Deferred tax is calculated using tax rates that have been substantively enacted at the reporting date. The effect on deferred tax of any changes in taxation rates is charged to the statement of comprehensive income, except to the extent that it relates to items previously charged directly to equity.
Deferred tax assets and liabilities are set off when there is a legally enforceable right to offset current tax assets against current tax liabilities and when they relate to income taxes levied by the same taxation authority and the group intends and has the ability to settle its current tax assets and liabilities on a net basis.