Depreciation should be provided on property, plant and equipment on a straight line basis (generally) from the time the asset is available for use, so as to write off the asset’s cost over the estimated useful life taking into account any expected residual value. Freehold land should not be subject to depreciation. All intangible assets, other than goodwill and assets with infinite lives, are amortised over their useful economic life. The method of amortisation reflects the pattern in which the assets are expected to be consumed. If the pattern cannot be determined reliably, the straight line method is used.