lowest 3-month rate
(2) Lowest 3-month rate applicable to any sale or exchange (A) In general In the case of any sale or exchange, the applicable Federal rate shall be the lowest 3-month rate. (B) Lowest 3-month rate For purposes of subparagraph (A), the term “lowest 3-month rate” means the lowest of the applicable Federal rates in effect for any month in the 3-calendar-month period ending with the 1st calendar month in which there is a binding contract in writing for such sale or exchange.