View all text of Subchapter C [§ 6621 - § 6622]
§ 6621. Determination of rate of interest
(a) General rule
(1) Overpayment rate
The overpayment rate established under this section shall be the sum of—
(A) the Federal short-term rate determined under subsection (b), plus
(B) 3 percentage points (2 percentage points in the case of a corporation).
To the extent that an overpayment of tax by a corporation for any taxable period (as defined in subsection (c)(3), applied by substituting “overpayment” for “underpayment”) exceeds $10,000, subparagraph (B) shall be applied by substituting “0.5 percentage point” for “2 percentage points”.
(2) Underpayment rate
The underpayment rate established under this section shall be the sum of—
(A) the Federal short-term rate determined under subsection (b), plus
(B) 3 percentage points.
(b) Federal short-term rate
For purposes of this section—
(1) General rule
(2) Period during which rate applies
(A) In general
(B) Special rule for individual estimated tax
(3) Federal short-term rate
(c) Increase in underpayment rate for large corporate underpayments
(1) In general
(2) Applicable date
For purposes of this subsection—
(A) In general
The applicable date is the 30th day after the earlier of—
(i) the date on which the 1st letter of proposed deficiency which allows the taxpayer an opportunity for administrative review in the Internal Revenue Service Independent Office of Appeals is sent, or
(ii) the date on which the deficiency notice under section 6212 is sent.
The preceding sentence shall be applied without regard to any such letter or notice which is withdrawn by the Secretary.
(B) Special rules
(i) Nondeficiency procedures
(ii) Exception where amounts paid in full
(iii) Exception for letters or notices involving small amounts
(3) Large corporate underpayment
For purposes of this subsection—
(A) In general
(B) Taxable period
For purposes of subparagraph (A), the term “taxable period” means—
(i) in the case of any tax imposed by subtitle A, the taxable year, or
(ii) in the case of any other tax, the period to which the underpayment relates.
(d)
(Added Pub. L. 93–625, § 7(a)(1), Jan. 3, 1975, 88 Stat. 2114; amended Pub. L. 94–455, title XIX, § 1906(b)(13)(A), Oct. 4, 1976, 90 Stat. 1834; Pub. L. 96–167, § 4(b), Dec. 29, 1979, 93 Stat. 1275; Pub. L. 97–34, title VII, § 711(a)–(c), Aug. 13, 1981, 95 Stat. 340; Pub. L. 97–248, title III, § 345(a), Sept. 3, 1982, 96 Stat. 636; Pub. L. 98–369, div. A, title I, § 144(a), July 18, 1984, 98 Stat. 682; Pub. L. 99–514, title XV, §§ 1511(a), (c)(1), 1535(a), Oct. 22, 1986, 100 Stat. 2744, 2750; Pub. L. 100–647, title I, § 1015(d), Nov. 10, 1988, 102 Stat. 3569; Pub. L. 101–239, title VII, § 7721(b), Dec. 19, 1989, 103 Stat. 2399; Pub. L. 101–508, title XI, § 11341(a), Nov. 5, 1990, 104 Stat. 1388–470; Pub. L. 103–465, title VII, § 713(a), Dec. 8, 1994, 108 Stat. 5001; Pub. L. 104–188, title I, § 1702(c)(6), (7), Aug. 20, 1996, 110 Stat. 1870; Pub. L. 105–34, title XIV, § 1463(a), title XVI, § 1604(b)(1), Aug. 5, 1997, 111 Stat. 1057, 1097; Pub. L. 105–206, title III, §§ 3301(a), 3302(a), July 22, 1998, 112 Stat. 741; Pub. L. 116–25, title I, § 1001(b)(1)(E), July 1, 2019, 133 Stat. 985.)