Independent Personal Services
(1) Income derived by an individual who is a resident of a Contracting State from the performance of personal services in an independent capacity shall be taxable only in that State, unless such services are performed or were performed in the other Contracting State and:
- (a) the income is attributable to a fixed base regularly available to the individual in that other State for the purpose of performing his activities; in such a case, the income attributable to that fixed base may be taxed in that other State; or
- (b) the individual is present in the other Contracting State for a period or periods exceeding in the aggregate 183 days in any twelve-month period.
(2) The term "personal services" includes especially independent scientific, literary, artistic,educational or teaching activities as well as the independent activities of physicians, lawyers, engineers, architects, dentists and accountants.