Fees for technical services: source-state may tax payments to nonresidents, subject to restrictions and PE exceptions. Article 12A permits the state where fees for technical services arise to tax such payments, with a limited source-state tax when the beneficial owner is resident in the other Contracting State. The Article defines the payments, excludes services covered by other Articles, disapplies source taxation where amounts are effectively connected to a permanent establishment or fixed base (invoking business profits or independent personal services rules), and subjects related party excess payments to arm's length adjustment.