Article 40 defines the tax scope for non-resident persons in Oman. Tax is charged on specific categories of income (defined in Article 52) accruing in Oman to non-residents who either: (1) do not have a permanent establishment (PE) in Oman, or (2) have a PE, but the specific income paid or credited to them is not considered part of that PE's gross income. This ensures that certain Omani-sourced payments, such as royalties or management fees, are taxed at the source when they do not fall under the standard corporate assessment of a local branch.