Article 88 establishes a specific annual depreciation rate for the transport sector. Capital expenditure incurred on the acquisition of any ship or aircraft used for business purposes during an accounting period is eligible for a depreciation deduction at a rate of 15% per year. This fixed rate provides a predictable schedule for the recovery of significant capital investments required for maritime and aviation operations in Oman, ensuring that the fiscal treatment of these high-value assets is consistent with their operational life and maintenance requirements.