AASB 136 Impairment of Assets 104-108: Impairment loss for a unit: recognise it only when the unit's recoverable amount is below its carrying amount, allocate it first to goodwill and then to other assets pro rata by carrying amount, never reducing an asset below its fair value less disposal costs, its value in use or zero, whichever is highest, treating each reduction as an individual asset loss; recognise any remainder as a liability only if another Standard requires

What does 104-108 require?

A loss is recognised for a unit, or for the smallest group of units carrying goodwill or a corporate asset, only when its recoverable amount falls short of its carrying amount. The loss first reduces whatever goodwill the unit carries and then the other assets of the unit in proportion to their carrying amounts, each reduction being an impairment loss on an individual asset recognised under paragraph 60. No asset is written down below the highest of three floors: fair value less disposal costs if measurable, value in use if determinable, and zero; and any loss that cannot be taken against that asset is reallocated pro rata to the other assets. Because the unit's assets work together, this allocation is necessarily arbitrary where individual recoverable amounts cannot be estimated. For an asset whose own recoverable amount cannot be determined, a loss is recognised only if its carrying amount exceeds both its fair value less disposal costs and the allocated result, and no loss at all is recognised if the unit is not impaired, even where the asset's fair value less disposal costs is below its carrying amount (though its depreciation may need review). After allocation, a liability is recognised for any remaining loss only if another Standard requires one.