26 USC 6699 - Failure to file S corporation return

(a) General rule 
In addition to the penalty imposed by section 7203 (relating to willful failure to file return, supply information, or pay tax), if any S corporation required to file a return under section 6037 for any taxable year
(1) fails to file such return at the time prescribed therefor (determined with regard to any extension of time for filing), or
(2) files a return which fails to show the information required under section 6037,

such S corporation shall be liable for a penalty determined under subsection (b) for each month (or fraction thereof) during which such failure continues (but not to exceed 12 months), unless it is shown that such failure is due to reasonable cause.

(b) Amount per month 
For purposes of subsection (a), the amount determined under this subsection for any month is the product of

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(1) $85, multiplied by
(2) the number of persons who were shareholders in the S corporation during any part of the taxable year.
(c) Assessment of penalty 
The penalty imposed by subsection (a) shall be assessed against the S corporation.
(d) Deficiency procedures not to apply 
Subchapter B of chapter 63 (relating to deficiency procedures for income, estate, gift, and certain excise taxes) shall not apply in respect of the assessment or collection of any penalty imposed by subsection (a).