26 C.F.R. § 509.106
In effect, Article IV of the convention provides that, if a Swiss enterprise by reason of its control of a United States enterprise imposes on the latter enterprise conditions different from those which would result from normal business relations between independent enterprises, the accounts between the enterprises shall be adjusted in order to ascertain the true taxable income of each enterprise. The purpose is to place the controlled United States enterprise on a tax parity with an uncontrolled United States enterprise by determining, according to the standard of an uncontrolled enterprise, the true taxable income from the property and business of the controlled enterprise. The basic objective of the article is that, if the accounting records do not truly reflect the taxable income from the property and business of the United States enterprise, the Commissioner shall intervene and, by making such distributions, apportionments, or allocations as he may deem necessary of gross income, deductions, credits, or allowances, or of any item or element affecting taxable income, between the United States enterprise and the Swiss enterprise by which it is controlled or directed, shall determine the true taxable income of the United States enterprise. The provisions of section 482 of the Internal Revenue Code of 1954, and the regulations thereunder, shall, insofar as applicable, be followed in the determination of the taxable income of the United States enterprise.
26 C.F.R. § 509.106