26 U.S.C. § 6672 : US Code - Section 6672: Failure to collect and pay over tax, or attempt to evade or defeat tax

    (a) General rule
      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
    (b) Preliminary notice requirement
      (1) In general
        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.
      (2) Timing of notice
        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.
      (3) Statute of limitations
        If a notice described in paragraph (1) with respect to any
      penalty is mailed or delivered in person before the expiration of
      the period provided by section 6501 for the assessment of such
      penalty (determined without regard to this paragraph), the period
      provided by such section for the assessment of such penalty shall
      not expire before the later of - 
          (A) the date 90 days after the date on which such notice was
        mailed or delivered in person, or
          (B) if there is a timely protest of the proposed assessment,
        the date 30 days after the Secretary makes a final
        administrative determination with respect to such protest.
      (4) Exception for jeopardy
        This subsection shall not apply if the Secretary finds that the
      collection of the penalty is in jeopardy.
    (c) Extension of period of collection where bond is filed
      (1) In general
        If, within 30 days after the day on which notice and demand of
      any penalty under subsection (a) is made against any person, such
      person - 
          (A) pays an amount which is not less than the minimum amount
        required to commence a proceeding in court with respect to his
        liability for such penalty,
          (B) files a claim for refund of the amount so paid, and
          (C) furnishes a bond which meets the requirements of
        paragraph (3),

      no levy or proceeding in court for the collection of the
      remainder of such penalty shall be made, begun, or prosecuted
      until a final resolution of a proceeding begun as provided in
      paragraph (2). Notwithstanding the provisions of section 7421(a),
      the beginning of such proceeding or levy during the time such
      prohibition is in force may be enjoined by a proceeding in the
      proper court. 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).
      (2) Suit must be brought to determine liability for penalty
        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) (!1) 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.

      (3) Bond
        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 1 1/2  times the amount of
      excess of the penalty assessed over the payment described in
      paragraph (1).
      (4) Suspension of running of period of limitations on collection
        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.
      (5) Jeopardy collection
        If the Secretary makes a finding that the collection of the
      penalty is in jeopardy, nothing in this subsection shall prevent
      the immediate collection of such penalty.
    (d) Right of contribution where more than 1 person liable for
      If more than 1 person is liable for the penalty under subsection
    (a) with respect to any tax, each person who paid such penalty
    shall be entitled to recover from other persons who are liable for
    such penalty an amount equal to the excess of the amount paid by
    such person over such person's proportionate share of the penalty.
    Any claim for such a recovery may be made only in a proceeding
    which is separate from, and is not joined or consolidated with - 
        (1) an action for collection of such penalty brought by the
      United States, or
        (2) a proceeding in which the United States files a
      counterclaim or third-party complaint for the collection of such
    (e) Exception for voluntary board members of tax-exempt
      No penalty shall be imposed by subsection (a) on any unpaid,
    volunteer member of any board of trustees or directors of an
    organization exempt from tax under subtitle A if such member - 
        (1) is solely serving in an honorary capacity,
        (2) does not participate in the day-to-day or financial
      operations of the organization, and
        (3) does not have actual knowledge of the failure on which such
      penalty is imposed.

    The preceding sentence shall not apply if it results in no person
    being liable for the penalty imposed by subsection (a).