16 Trade and other receivables
Trade and other receivables have been analysed between non-current and current as follows:
Ageing of gross receivables
The following table provides information regarding the ageing of gross receivables:
The above analysis in respect of gross trade receivables reconciles to net trade receivables by deduction of the allowance for doubtful receivables of £192.8 million (2008: £171.7 million).
The group manages its regulated bad debt risk by providing against gross trade receivables. This allowance is calculated by reference to customer categories rather than on the age profile of gross debtor balances. It is therefore not possible to age the allowance for doubtful receivables.
Amounts owed by subsidiary undertakings is a sum of all subsidiary balances where the total of debt and interest is in a net receivable position.
Amounts owed by subsidiary undertakings are shown net of an allowance for doubtful receivables of £nil. Any allowance for doubtful receivables is determined by a detailed review of balances due on a company by company basis and by reference to the ongoing activities of each company within the group.
Trade and other receivables is split as follows:
The directors consider that the carrying amount of trade and other receivables approximates to their fair value, at both 31 March 2009 and 31 March 2008.
The group’s average credit period taken on sales is 31 days (2008: 33 days).