Dependent personal services rule limits source-state taxation when presence is limited and employer is non resident, with PE safeguards. Article 15 provides that employment income is taxable in the taxpayer's State of residence unless the employment is exercised in the other Contracting State, in which case the other State may tax it; however, residence-state taxation prevails if presence in the other State is limited, the employer is non-resident there, and the remuneration is not borne by the employer's permanent establishment or fixed base in that other State, with a specific rule permitting taxation by the enterprise's State for employment on ships or aircraft in international traffic.