Article 1 provides comprehensive definitions for terms used throughout the Oman Income Tax Law. Key definitions include 'Authority' (Tax Authority), 'Tax Year' (calendar year), and 'Taxpayer' (enterprises, Omani companies, or permanent establishments). It clarifies 'Permanent Establishment' by referencing Articles 2 and 3, and defines 'Gross Income' and 'Taxable Income' per Articles 42 and 43. Specific activities like 'Professional Activity' and 'Business' are broad, covering commercial, industrial, and vocational pursuits. Critically, it defines 'Petroleum' and 'Residency' conditions, ensuring a foundational legal framework for applying tax charges, administrative penalties, and assessment procedures under Royal Decree 118/2020.