NOTES TO THE CONSOLIDATED FINANCIAL STATEMENTS CONT 3. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED) (k) Impairment (continued) (i) Non-financial assets (continued) (ii) Financial assets (l) Intangible assets (i) Goodwill (ii) Acquired intangible assets (m) Trade and other payables Annual Report 2013 63 Trade and other payables are carried at amortised cost and due to their short-term nature they are not discounted� They represent liabilities  for goods and services provided to us prior to the end of the financial year that are unpaid and arise when we become obliged to make future  payments in respect of the purchase of these goods and services� Trade payables are unsecured and are usually paid within 30 days of recognition�  Other payables are unsecured and are usually paid within 90 days of recognition� Intangible assets with indefinite useful lives are tested for impairment annually either individually or at the cash-generating unit level� These  intangibles are not amortised� The useful life of an intangible asset with an indefinite life is reviewed each reporting period to determine whether  indefinite life assessment continues to be supportable� If not, the change in the useful life assessment from indefinite to finite is accounted for as a  change in an accounting estimate and is thus accounted for on a prospective basis�  The useful lives of intangible assets are assessed to be either finite or indefinite� Intangible assets with finite lives are amortised over their useful  life and tested for impairment whenever there is an indication that the intangible asset may be impaired (see note (k) for methodology)� The  amortisation period and the amortisation method for an intangible asset with a finite useful life is reviewed at least at each financial year end�  Changes in the expected useful life or the expected pattern of consumption of future economic benefits embodied in the asset are accounted  for prospectively by changing the amortisation period or method, as appropriate, which is a change in accounting estimate� The amortisation  expense on intangible assets with finite lives is recognised in the income statement in the expense category consistent with the function of the  intangible asset� Intangible assets acquired separately or in a business combination are initially measured at cost� The cost of an intangible asset acquired in a  business combination is its fair value as at the date of acquisition� Following initial recognition, intangible assets are carried at cost less any  accumulated amortisation and any accumulated impairment losses� Internally generated intangible assets, excluding capitalised development  costs, are not capitalised and expenditure is recognised in the income statement in the year in which the expenditure is incurred�  After initial recognition, goodwill is measured at cost less any accumulated impairment losses and is tested for impairment in accordance with note  (k) on an annual basis, or when an indication of impairment exists� Goodwill acquired in a business combination is initially measured at cost of the business combination being the excess of the consideration  transferred over the fair value of the net identifiable assets we have acquired and the liabilities we have assumed� If this consideration transferred  is lower than the fair value of the net identifiable assets of the subsidiary acquired, the difference is recognised in the income statement� Intangible assets are assets that have value, but do not have physical substance� In order to be recognised, an intangible asset must be either  separable or arise from contractual or other legal rights� At each reporting date we assess whether there is objective evidence to suggest that any of our financial assets are impaired� For financial assets  held at cost or amortised cost (trade and other receivables), we consider the financial asset to be impaired when there is objective evidence as  a result of one or more events that the present value of estimated discounted future cash flows is lower than the carrying value� Any impairment  losses are recognised immediately in the income statement� In determining value in use, we apply management judgement in establishing forecasts of future operating performance, as well as the selection  of growth rates, terminal rates and discount rates� These judgements are applied based on our understanding of historical information and  expectations of future performance� The expected net cash flows included in determining recoverable amounts of our assets are discounted to  present values using a market determined, risk adjusted, discount rate�