Section 6166(g)(3) provides:
(g) Acceleration of payment
. . . . . . . . . .
(3) Failure to make payment of principal or interest
(A) In general
Except as provided in subparagraph (B), if any payment of principal or interest under this section is not paid on or before the date fixed for its payment by this section (including any extension of time), the unpaid portion of the tax payable in installments shall be paid upon notice and demand from the Secretary.
(B) Payment within 6 months
If any payment of principal or interest under this section is not paid on or before the date determined under subparagraph (A) but is paid within 6 months of such date-
The penalty imposed under clause (iii) shall be treated in the same manner as a penalty imposed under subchapter B of chapter 68.
Section 6166(g)(3) Overview, Comment 1: If the late payment and penalty are not paid within 6 months of the anniversary due date, and the account is accelerated by IRS, the penalty assessed will automatically abate. Payment of the penalty within 6 months is required in order to save the section 6166 election. If the election is terminated for nonpayment, a penalty is no longer appropriate under section 6166(g)(3)(B)(iii).