According to the accrual basis, expenses should be recognised in the period in which they are incurred.
Tax expense should therefore be recognised in the period in which it is incurred, not when tax is paid income profit from accounting profit, the current tax expense will not necessarily reflect the accounting tax.
Due to tax legislation resulting in differences in taxable x expense in the correct accounting period (even if there are no permanent differences).
Deferred tax ensures that the total tax expense recognised relates to the period in which the accounting profit is made.