Pappas & Associates, P.A.

§6672 of the Internal Revenue Code imposes a 20% penalty on a taxpayer’s substantial understatement of income tax:

(d) Substantial understatement of income tax

(1) Substantial understatement

(A) In general
For purposes of this section, there is a substantial understatement of income tax for any taxable year if the amount of the understatement for the taxable year exceeds the greater of—

(i) 10 percent of the tax required to be shown on the return for the taxable year, or

(ii) $5,000.

(B) Special rule for corporations
In the case of a corporation other than an S corporation or a personal holding company (as defined in section 542), there is a substantial understatement of income tax for any taxable year if the amount of the understatement for the taxable year exceeds the lesser of—

(i) 10 percent of the tax required to be shown on the return for the taxable year (or, if greater, $10,000), or

(ii) $10,000,000.