100 STAT. 2744
PUBLIC LAW 99-514—OCT. 22, 1986
Subtitle B—Interest Provisions SEC. 1511. DIFFERENTIAL INTEREST RATE.
(a) GENERAL RULE.—Section 6621 (relating to determination of rate of interest) is amended by striking out subsections (a), (b), and (c) and inserting in lieu thereof the following: "(a) GENERAL RULE.— "(1) OVERPAYMENT RATE.—The overpayment rate established
under this section shall be the sum of— "(A) the short-term Federal rate determined under .,,, subsection (b), plus "(B) 2 percentage points. "(2) UNDERPAYMENT RATE.—The underpayment rate established under this section shall be the sum of— "(A) the short-term Federal rate determined under subsection (b), plus "(B) 3 percentage points. "(b) SHORT-TERM FEDERAL RATE.—For purposes of this section— "(1) GENERAL RULE.—The Secretary shall determine the shortterm Federal rate for the first month in each calendar quarter. "(2) PERIOD DURING WHICH RATE APPLIES.—
"(A) IN GENERAL.—Except as provided in subparagraph (B), the Federal short-term rate determined under paragraph (1) for any month shall apply during the first calendar quarter beginning after such month. "(B) SPECIAL RULE FOR INDIVIDUAL ESTIMATED TAX.—In
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determining the addition to tax under section 6654 for ^ failure to pay estimated tax for any taxable year, the Federal short-term rate which applies during the 3rd month following such taxable year shall also apply during
- the first 15 days of the 4th month following such taxable
year. "(3) FEDERAL SHORT-TERM RATE.—The Federal short-term rate for any month shall be the Federal short-term rate determined « during such month by the Secretary in accordance with section 1274(d). Any such rate shall be rounded to the nearest full percent (or, if a multiple of V of 1 percent, such rate shall be 2 increased to the next highest full percent)." (b) COORDINATION BY REGULATION.—The Secretary of the Treasury
or his delegate may issue regulations to coordinate section 6621 of the Internal Revenue Code of 1954 (as amended by this section) with section 6601(f) of such Code. Such regulations shall not apply to any period after the date 3 years after the date of the enactment of this Act. (c) TECHNICAL AMENDMENTS.—
(1) Section 6621 is amended— (A) by redesignating subsection (d) as subsection (c), and .:-, (B) by striking out "the adjusted rate established under subsection (b)" in subsection (c)(1) (as so redesignated) and inserting in lieu thereof "the underpayment rate established under this section", and (C) by striking out "annual" in subsection (c)(1) (as so redesignated). (2) Subparagraph (G) of section 47(d)(3) is amended by striking out "determined under section 6621" and inserting in lieu
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