The term “stated redemption price at maturity” means the amount fixed by the last modification of the purchase agreement and includes interest and other amounts payable at that time (other than any interest based on a fixed rate, and payable unconditionally at fixed periodic intervals of 1 year or less during the entire term of the debt instrument).
26 U.S. Code § 1273. Determination of amount of original issue discount
Amendment by Pub. L. 99–514 effective, except as otherwise provided, as if included in the provisions of the Tax Reform Act of 1984, Pub. L. 98–369, div. A, to which such amendment relates, see section 1881 of Pub. L. 99–514, set out as a note under section 48 of this title.
For provisions directing that if any amendments made by subtitle A or subtitle C of title XI [§§ 1101–1147 and 1171–1177] or title XVIII [§§ 1800–1899A] of Pub. L. 99–514 require an amendment to any plan, such plan amendment shall not be required to be made before the first plan year beginning on or after Jan. 1, 1989, see section 1140 of Pub. L. 99–514, as amended, set out as a note under section 401 of this title.