26 U.S.C. § 6719: Failure to register or reregister

(a) Failure to register or reregisterEvery person who is required to register or reregister under section 4101 and fails to do so shall pay a penalty in addition to the tax (if any). (b) Amount of penaltyThe amount of the penalty under subsection (a) shall be—(1) $10,000 for each initial failure to register or reregister, and (2) $1,000 for each day thereafter such person fails to register or reregister. (c) Reasonable cause exceptionNo penalty shall be imposed under this section with respect to any failure if it is shown that such failure is due to reasonable cause.