In accounting, goodwill is recorded when an acquiring entity purchases a target company for more than the fair value of its net identifiable assets during business combination. IAS 36 - Impairment of Assets sets out requirements for impairment which cover a range of assets including goodwill.
Timing
Goodwill is recorded as an intangible asset and evaluated periodically (at least once annually) for any possible impairment in value. Goodwill does not have to be tested for impairment at the year end. Impairment assessment can be updated earlier if there is any impairment indicator arising between the assessment date and the year-end date.
Impairment loss
Impairment loss is the amount by which the carrying amount of an asset or cash-generating unit exceeds its recoverable amount, i.e. the higher of its fair value less costs to sell of disposal and its value in use.
Value in use
Value in use is the present value of the future cash flows expected to be derived from an asset or cash-generating unit.
Cash flow projections should be based on reasonable and supportable assumptions, the most recent budgets and forecasts, and extrapolation for periods beyond budgeted projections. Cash flow projections should relate to the asset in its current condition. Estimates of future cash flows should not include cash inflows or outflows from financing activities, or income tax receipts or payments.