(A) In general The applicable date is the 30th day after the earlier of
(i) the date on which the 1st letter of proposed deficiency which allows the taxpayer an opportunity for administrative review in the Internal Revenue Service Office of Appeals is sent, or
(ii) the date on which the deficiency notice under section
6212 is sent.
The preceding sentence shall be applied without regard to any such letter or notice which is withdrawn by the Secretary.
(B) Special rules
(i) Nondeficiency procedures In the case of any underpayment of any tax imposed by this title to which the deficiency procedures do not apply, subparagraph (A) shall be applied by taking into account any letter or notice provided by the Secretary which notifies the taxpayer of the assessment or proposed assessment of the tax.
(ii) Exception where amounts paid in full For purposes of subparagraph (A), a letter or notice shall be disregarded if, during the 30-day period beginning on the day on which it was sent, the taxpayer makes a payment equal to the amount shown as due in such letter or notice, as the case may be.
(iii) Exception for letters or notices involving small amounts For purposes of this paragraph, any letter or notice shall be disregarded if the amount of the deficiency or proposed deficiency (or the assessment or proposed assessment) set forth in such letter or notice is not greater than $100,000 (determined by not taking into account any interest, penalties, or additions to tax).