The starting point for scrutinising transfer prices would frequently be the appearance of a discrepancy between the profits returned by an associated enterprise and those which might be expected to be made by comparable enterprises in the uncontrolled situation. Since the assessment of an arm’s length price depends very often on careful judgement and the resolution of many, perhaps conflicting, considerations by negotiation between the tax authorities and the enterprise concerned, it follows that if the prices actually paid can be substantiated by acceptable evidence as being arm’s length prices there would be no justification for seeking to make merely minor or marginal adjustments to them for tax purposes. Similarly a tax authority should hesitate to disturb without good reason a pricing arrangement reasonably and consistently operated between associated enterprises if it is also reasonably and consistently operated in comparable dealings with independent parties. Moreover, as a general principle, tax authorities should base their search for an arm’s length price on actual transactions and should not substitute hypothetical transactions for them, thus seeming to substitute their own commercial judgement for that of the enterprise at the time when the transactions were concluded (though there may be some circumstances where the form of transaction has effectively to be ignored – see paragraphs 23 and 24).