Article 84 sets a primary condition for claiming depreciation on buildings, ships, aircraft, and intangible assets. Depreciation is only allowed if the asset was used for business purposes during the accounting period and remains in use for those purposes until the very end of that period. If an asset is disposed of or ceases to be used before the end of the accounting period, the standard annual depreciation deduction for that specific year is generally disallowed. This ensures that tax relief for the gradual wear and tear of an asset is only granted for ongoing business operations.