In certain cases, the arm’s length principle may result in an administrative burden for both the taxpayer and the tax administrations of evaluating significant numbers and types of cross-border transactions. Although associated enterprises normally establish the conditions for a transaction at the time it is undertaken, at some point the enterprises may be required to demonstrate that these are consistent with the arm’s length principle. (See discussion of timing and compliance issues at Sections B and C of Chapter III and at Chapter V on Documentation). The tax administration may also have to engage in this verification process perhaps some years after the transactions have taken place. The tax administration would review any supporting documentation prepared by the taxpayer to show that its transactions are consistent with the arm’s length principle, and may also need to gather information about comparable uncontrolled transactions, the market conditions at the time the transactions took place, etc., for numerous and varied transactions. Such an undertaking usually becomes more difficult with the passage of time.