post-termination transition period
(1) In general For purposes of this subchapter, the term “post-termination transition period” means— (A) the period beginning on the day after the last day of the corporation’s last taxable year as an S corporation and ending on the later of— (i) the day which is 1 year after such last day, or (ii) the due date for filing the return for such last year as an S corporation (including extensions), (B) the 120-day period beginning on the date of any determination pursuant to an audit of the taxpayer which follows the termination of the corporation’s election and which adjusts a subchapter S item of income, loss, or deduction of the corporation arising during the S period (as defined in section 1368(e)(2) ), and (C) the 120-day period beginning on the date of a determination that the corporation’s election under section 1362(a) had terminated for a previous taxable year.