§ 6664. Definitions and special rules
(a)
Underpayment
For purposes of this part, the term “underpayment” means the amount by which any tax imposed by this title exceeds the excess of—
For purposes of paragraph (2), the term “rebate” means so much of an abatement, credit, refund, or other repayment, as was made on the ground that the tax imposed was less than the excess of the amount specified in paragraph (1) over the rebates previously made.
(c)
Reasonable cause exception for underpayments
(3)
Special rule for certain valuation overstatements
In the case of any underpayment attributable to a substantial or gross valuation overstatement under chapter 1 with respect to charitable deduction property, paragraph (1) shall not apply. The preceding sentence shall not apply to a substantial valuation overstatement under chapter 1 if—
(4)
Definitions
For purposes of this subsection—
(A)
Charitable deduction property
The term “charitable deduction property” means any property contributed by the taxpayer in a contribution for which a deduction was claimed under section
170. For purposes of paragraph (3), such term shall not include any securities for which (as of the date of the contribution) market quotations are readily available on an established securities market.
(B)
Qualified appraisal
The term “qualified appraisal” has the meaning given such term by section
170
(f)(11)(E)(i).
(C)
Qualified appraiser
The term “qualified appraiser” has the meaning given such term by section
170
(f)(11)(E)(ii).
(d)
Reasonable cause exception for reportable transaction understatements
(1)
In general
No penalty shall be imposed under section
6662A with respect to any portion of a reportable transaction understatement if it is shown that there was a reasonable cause for such portion and that the taxpayer acted in good faith with respect to such portion.
(3)
Special rules
Paragraph (1) shall not apply to any reportable transaction understatement unless—
(A)
the relevant facts affecting the tax treatment of the item are adequately disclosed in accordance with the regulations prescribed under section
6011,
(4)
Rules relating to reasonable belief
For purposes of paragraph (3)(C)—
(A)
In general
A taxpayer shall be treated as having a reasonable belief with respect to the tax treatment of an item only if such belief—
(B)
Certain opinions may not be relied upon
(i)
In general
An opinion of a tax advisor may not be relied upon to establish the reasonable belief of a taxpayer if—
(ii)
Disqualified tax advisors
A tax advisor is described in this clause if the tax advisor—
(I)
is a material advisor (within the meaning of section
6111
(b)(1)) and participates in the organization, management, promotion, or sale of the transaction or is related (within the meaning of section
267
(b) or
707
(b)(1)) to any person who so participates,
(iii)
Disqualified opinions
For purposes of clause (i), an opinion is disqualified if the opinion—
(I)
is based on unreasonable factual or legal assumptions (including assumptions as to future events),