26 CFR § 1.145-1 - Qualified 501(c)(3) bonds.
(a) Overview. Interest on a private activity bond is not excludable from gross income under section 103(a) unless the bond is a qualified bond. Under section 141(e)(1)(G), a qualified 501(c)(3) bond issued under section 145 is a qualified bond. Under section 145, a qualified 501(c)(3) bond is any bond issued as a part of an issue that satisfies the requirements of sections 145(a) through (d).