Article 91 establishes the legal right for taxpayers to claim a depreciation deduction for capital expenditure on any machinery, plant, or other capital assets falling within the three pools defined in Article 90. This deduction is available for any accounting period during which the pooled assets were used for the purposes of the business. By linking the deduction directly to the pools, the Law ensures that the accelerated 33% rate or the standard 15% and 10% rates are applied systematically to the entity's productive equipment and technology investments.