Discounted cash flow models of the fair market value of transferred intangible assets must rely on the estimated cash flows from the intangible asset over its economic useful life. Even if a reliable forecast of future sales and expenses from an enterprise were available, the representatives of the multinational must defend its assumptions with respect to the share of profits attributable to the transferred intangible, the economic useful life for the transferred intangible assets, and the appropriate discount rate. The IRS has challenged certain applications of this approach on the grounds that the representatives of the multinational have understated the share of profits attributable to the transferred intangible and the economic useful life while overstating the appropriate discount rate.