26 U.S. Code § 6672 - Failure to collect and pay over tax, or attempt to evade or defeat tax
Any person required to collect, truthfully account for, and pay over any tax imposed by this title who willfully fails to collect such tax, or truthfully account for and pay over such tax, or willfully attempts in any manner to evade or defeat any such tax or the payment thereof, shall, in addition to other penalties provided by law, be liable to a penalty equal to the total amount of the tax evaded, or not collected, or not accounted for and paid over. No penalty shall be imposed under section 6653 or part II of subchapter A of chapter 68 for any offense to which this section is applicable.
No penalty shall be imposed under subsection (a) unless the Secretary notifies the taxpayer in writing by mail to an address as determined under section 6212(b) or in person that the taxpayer shall be subject to an assessment of such penalty.
The mailing of the notice described in paragraph (1) (or, in the case of such a notice delivered in person, such delivery) shall precede any notice and demand of any penalty under subsection (a) by at least 60 days.
If, within 30 days after the day on which his claim for refund with respect to any penalty under subsection (a) is denied, the person described in paragraph (1) fails to begin a proceeding in the appropriate United States district court (or in the Court of Claims)  for the determination of his liability for such penalty, paragraph (1) shall cease to apply with respect to such penalty, effective on the day following the close of the 30-day period referred to in this paragraph.
The bond referred to in paragraph (1) shall be in such form and with such sureties as the Secretary may by regulations prescribe and shall be in an amount equal to 1½ times the amount of excess of the penalty assessed over the payment described in paragraph (1).
The running of the period of limitations provided in section 6502 on the collection by levy or by a proceeding in court in respect of any penalty described in paragraph (1) shall be suspended for the period during which the Secretary is prohibited from collecting by levy or a proceeding in court.
 See References in Text note below.
The Court of Claims, referred to in subsec. (c)(2), and the United States Court of Customs and Patent Appeals were merged effective Oct. 1, 1982, into a new United States Court of Appeals for the Federal Circuit by Pub. L. 97–164, Apr. 2, 1982, 96 Stat. 25, which also created a United States Claims Court [now United States Court of Federal Claims] that inherited the trial jurisdiction of the Court of Claims. See sections 48, 171 et seq., 791 et seq., and 1491 et seq. of Title 28, Judiciary and Judicial Procedure.
1998—Subsec. (b)(1). Pub. L. 105–206, § 3307(a), inserted “or in person” after “section 6212(b)”.
Subsec. (b)(2). Pub. L. 105–206, § 3307(b)(1), inserted “(or, in the case of such a notice delivered in person, such delivery)” after “paragraph (1)”.
Subsec. (b)(3). Pub. L. 105–206, § 3307(b)(2), inserted “or delivered in person” after “mailed” in introductory provisions and in subpar. (A).
1996—Subsecs. (b), (c). Pub. L. 104–168, § 901(a), added subsec. (b) and redesignated former subsec. (b) as (c).
Subsec. (d). Pub. L. 104–168, § 903(a), added subsec. (d).
Subsec. (e). Pub. L. 104–168, § 904(a), added subsec. (e).
1989—Subsec. (a). Pub. L. 101–239, § 7721(c)(9), inserted “or part II of subchapter A of chapter 68” after “under section 6653”.
Subsec. (b)(1). Pub. L. 101–239, § 7737(a), inserted at end “Nothing in this paragraph shall be construed to prohibit any counterclaim for the remainder of such penalty in a proceeding begun as provided in paragraph (2).”
1978—Pub. L. 95–628 designated existing provisions as subsec. (a), added subsec. (a) heading, and added subsec. (b).
Amendment by section 7721(c)(9) of Pub. L. 101–239 applicable to returns the due date for which (determined without regard to extensions) is after Dec. 31, 1989, see section 7721(d) of Pub. L. 101–239, set out as a note under section 461 of this title.