(a) In general
Unless otherwise provided in regulations, all determinations under this subtitle shall be made in the taxpayer’s functional currency.
(b) Functional currency
(1) In generalFor purposes of this subtitle, the term “functional currency” means—
in the case of a qualified business unit, the currency of the economic environment in which a significant part of such unit’s activities are conducted and which is used by such unit in keeping its books and records.
(2) Functional currency where activities primarily conducted in dollars
(3) ElectionTo the extent provided in regulations, the taxpayer may elect to use the dollar as the functional currency for any qualified business unit if—
Any such election shall apply to the taxable year for which made and all subsequent taxable years unless revoked with the consent of the Secretary.