25 Additions The cost of an item of property, plant and equipment is recognised as an asset only when it is probable that future economic benefits or service potential associated with the item will flow to the Commission and the cost of the item can be measured reliably. Disposals Gains and losses on disposals are determined by comparing the proceeds with the carrying amount of the asset. Gains and losses on disposals are included in the statement of financial performance. When revalued assets are sold, the amounts included in revaluation reserves in respect of those assets are transferred to general Subsequent costs Costs incurred subsequent to initial acquisition are capitalised only when it is probable that future economic benefits or service potential associated with the item will flow to the Law Commission and the cost of the item can be measured reliably. The costs of day-to-day servicing of property, plant and equipment are recognised in the statement of financial performance as they are incurred. Depreciation Depreciation is provided on a straight-line basis on all property, plant and equipment other than land, at rates that will write off the cost (or valuation) of the assets to their estimated values over their useful lives. The useful lives and associated depreciation rates of major classes of assets have been estimated as follows: Computer equipment 3 years   (33.33%) Office equipment 5 years   (20%) Furniture and fittings 10 years (10% Library collection 5 years   (20%) The residual value and useful life of an asset is reviewed, and adjusted if applicable, at each financial year-end. Intangible assets Software acquisition Acquired computer software licenses are capitalised on the basis of the costs incurred to acquire and bring to use the specific software. Staff training costs are recognised as an expense when incurre