disputable tax
(2) Disputable tax (A) In general For purposes of this section, the term “disputable tax” means the amount of tax specified at the time of the deposit as the taxpayer’s reasonable estimate of the maximum amount of any tax attributable to disputable items. (B) Safe harbor based on 30-day letter In the case of a taxpayer who has been issued a 30-day letter, the maximum amount of tax under subparagraph (A) shall not be less than the amount of the proposed deficiency specified in such letter.