Article 89 governs the depreciation of intangible assets, excluding computer software and intellectual property which are pooled separately under Article 90. For other intangible assets used in business, the annual deduction is calculated using the straight-line method. The total capital expenditure is divided by the number of years of the asset's 'productive life'. The determination of this productive life is at the discretion of the Tax Authority. This ensures that the tax relief for intangible investments (such as licenses or rights) matches the actual economic benefit the asset provides to the business.