Article 135 establishes the universal requirement for electronic tax returns. Taxpayers are obligated to file a return for any tax year in which an accounting period ends, declaring their taxable income. Notably, this obligation persists even during periods of tax exemption; entities enjoying a tax holiday must still comply with filing requirements. This ensures the Tax Authority maintains continuous oversight of all business activities and can verify that the conditions for any exemptions are being met throughout the entire duration of the entity's operations in Oman.