If the S corporation has no subchapter C earnings and profits at the close of the taxable year (because, for example, such earnings and profits were distributed in accordance with section 1368), the tax shall not be imposed even though the S corporation has passive investment income for the taxable year. If the tax is imposed, the tax shall be computed by multiplying the excess net passive income (as defined in paragraph (b) of this section) by the highest rate of tax specified in section 11(b).
Where:
ENPI = excess net passive income
NPI = net passive income
PII = passive investment income
GR = total gross receipts
the amount of such gain taken into account under section 1374(b) and § 1.1374-1(b) (1) and (2) in determining the amount of tax shall be reduced by the portion of the excess net passive income for the taxable year which is attributable (on a pro rata basis) to such gain. For purposes of the preceding sentence, the portion of excess net passive income for the taxable year which is attributable to such capital gain is equal to the amount determined by multiplying the excess net passive income by the following fraction:
Where:
NCG = net capital gain
NPI = net passive income.
E = Expense attributable to net capital gain.
the Commissioner may waive the tax imposed by section 1375 for such taxable year. The S corporation has the burden of establishing that under the relevant facts and circumsances the Commissioner should waive the tax.
For example, if an S corporation establishes that in good faith and using due diligence it determined that it had no subchapter C earnings and profits at the close of a taxable year, but it was later determined on audit that it did have subchapter C earnings and profits at the close of such taxable year, and if the corporation establishes that it distributed such earnings and profits within a reasonable time after the audit, it may be appropriate for the Commissioner to waive the tax on passive income for such taxable year.
26 C.F.R. §1.1375-1