26 USC 6675 - Excessive claims with respect to the use of certain fuels

(a) Civil penalty 
In addition to any criminal penalty provided by law, if a claim is made under section 6416 (a)(4) (relating to certain sales of gasoline), section 6420 (relating to gasoline used on farms), 6421 (relating to gasoline used for certain nonhighway purposes or by local transit systems), or 6427 (relating to fuels not used for taxable purposes) for an excessive amount, unless it is shown that the claim for such excessive amount is due to reasonable cause, the person making such claim shall be liable to a penalty in an amount equal to whichever of the following is the greater:
(1) Two times the excessive amount; or
(2) $10.
(b) Excessive amount defined 
For purposes of this section, the term excessive amount means in the case of any person the amount by which

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(1) the amount claimed under section 6416 (a)(4), 6420, 6421, or 6427, as the case may be, for any period, exceeds
(2) the amount allowable under such section for such period.
(c) Assessment and collection of penalty 
For assessment and collection of penalty provided by subsection (a), see section 6206.