Stocks Stocks are stated at the lower of cost and net realisable value, being the estimated selling price less costs to complete and sell. Cost is based on the cost of purchase on a first in, first out basis. Work in progress and finished goods include labour and attributable overheads. At each balance sheet date, stocks are assessed for impairment. If stock is impaired, the carrying amount is reduced to its selling price less costs to complete and sell. The impairment loss is recognised immediately in profit or loss. Provisions for liabilities Provisions are recognised when an event has taken place that gives rise to a legal or constructive obligation, a transfer of economic benefits is probable and a reliable estimate can be made. Provisions are measured as the best estimate of the amount required to settle the obligation, taking into account the related risks and uncertainties. Increases in provisions are generally charged as an expense to profit or loss. Current and deferred taxation The tax expense for the year comprises current and deferred tax. Tax is recognised in profit or loss except that a charge attributable to an item of income and expense recognised as other comprehensive income or to an item recognised directly in equity is also recognised in other comprehensive income or directly in equity respectively. The current income tax charge is calculated on the basis of tax rates and laws that have been enacted or substantively enacted by the balance sheet date in the countries where the Company operates and generates income. Deferred tax balances are recognised in respect of all timing differences that have originated but not reversed by the balance sheet date, except that: The recognition of deferred tax assets is limited to the extent that it is probable that they will be recovered against the reversal of deferred tax liabilities or other future taxable profits; and Any deferred tax balances are reversed if and when all conditions for retaining associated tax allowances have been met. Deferred tax balances are not recognised in respect of permanent differences except in respect of business combinations, when deferred tax is recognised on the differences between the fair values of assets acquired and the future tax deductions available for them and the differences between the fair values of liabilities acquired and the amount that will be assessed for tax. Deferred tax is determined using tax rates and laws that have been enacted or substantively enacted by the balance sheet date.