1. Income derived by an individual who is a resident of a Contracting State in respect of professional services or other activities of an independent character shall be taxable only in that Contracting State, unless he has a fixed base regularly available to him in the other Contracting State for the purpose of performing his activities or he is present in that other Contracting State for a period or periods exceeding in the aggregate 183 days in the calendar year concerned. If he has such a fixed base or remains in that other Contracting State for the aforesaid period or periods, the income may be taxed in that other Contracting State, but only so much of it as is attributable to that fixed base or is derived in that other Contracting State during the aforesaid period or periods.
2. The term 「professional 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.