§ 171.
(a)
General rule
In the case of any bond, as defined in subsection (d), the following rules shall apply to the amortizable bond premium (determined under subsection (b)) on the bond:
(e)
Treatment as offset to interest payments
Except as provided in regulations, in the case of any taxable bond—
(1)
the amount of any bond premium shall be allocated among the interest payments on the bond under rules similar to the rules of subsection (b)(3), and
(2)
in lieu of any deduction under subsection (a), the amount of any premium so allocated to any interest payment shall be applied against (and operate to reduce) the amount of such interest payment.
For purposes of the preceding sentence, the term “taxable bond” means any bond the interest of which is not excludable from gross income.
([Aug. 16, 1954, ch. 736], [68A Stat. 61]; [Pub. L. 85–866, title I, § 13(a)], Sept. 2, 1958, [72 Stat. 1610]; [Pub. L. 94–455, title XIX], §§ 1901(b)(1)(E), 1906(b)(13)(A), 1951(b)(5)(A), Oct. 4, 1976, [90 Stat. 1790], 1834, 1837; [Pub. L. 99–514, title VI, § 643(a)], title XVIII, § 1803(a)(11)(A), (B), (12)(A), Oct. 22, 1986, [100 Stat. 2285], 2795; [Pub. L. 100–647, title I, § 1006(j)(1)(A)], Nov. 10, 1988, [102 Stat. 3411]; [Pub. L. 108–357, title IV, § 413(c)(2)], Oct. 22, 2004, [118 Stat. 1507]; [Pub. L. 113–295, div. A, title II, § 221(a)(29)], Dec. 19, 2014, [128 Stat. 4041].)