Article 85 defines depreciation as a recognized business expense for any accounting period. It requires that the annual depreciation amount must be proportionately increased or decreased if the accounting period is longer or shorter than one calendar year, or if the business was only operational for part of the year. Crucially, the Article establishes an absolute ceiling: the total accumulated depreciation allowed for any asset over its life cannot exceed the original capital expenditure incurred for its acquisition. This prevents over-recovery of the asset's cost through the tax system.