the date of notification to the employer under section 1399(b)(2)(B) of this title, or

120 days after the date of the employer’s request under section 1399(b)(2)(A) of this title.

For purposes of any proceeding under this section, any determination made by a plan sponsor under sections 1381 through 1399 of this title and section 1405 of this title is presumed correct unless the party contesting the determination shows by a preponderance of the evidence that the determination was unreasonable or clearly erroneous.

such determination is based in whole or in part on a finding by the plan sponsor under section 1392(c) of this title that a principal purpose of a transaction that occurred before January 1, 1999, was to evade or avoid withdrawal liability under this subtitle, and

such transaction occurred at least 5 years before the date of the complete or partial withdrawal,

such determination is based in whole or in part on a finding by the plan sponsor under section 1392(c) of this title that a principal purpose of any transaction which occurred after December 31, 1998, and at least 5 years (2 years in the case of a small employer) before the date of the complete or partial withdrawal was to evade or avoid withdrawal liability under this subtitle,

provides notice to the plan sponsor of its election to apply the special rule in this paragraph within 90 days after the plan sponsor notifies the electing person of its liability by reason of the application of section 1392(c) of this title; and

if a final decision in the arbitration proceeding, or in court, of the withdrawal liability dispute has not been rendered within 12 months from the date of such notice, the electing person provides to the plan, effective as of the first day following the 12-month period, a bond issued by a corporate surety company that is an acceptable surety for purposes of section 1112 of this title, or an amount held in escrow by a bank or similar financial institution satisfactory to the plan, in an amount equal to the sum of the withdrawal liability payments that would otherwise be due under subsection (d) and section 1399(c) of this title for the 12-month period beginning with the first anniversary of such notice. Such bond or escrow shall remain in effect until there is a final decision in the arbitration proceeding, or in court, of the withdrawal liability dispute, at which time such bond or escrow shall be paid to the plan if such final decision upholds the plan sponsor’s determination.

Any group treated as a single employer under subsection (b)(1) of section 1301 of this title, without regard to any transaction that was a basis for the plan’s finding under section 1392 of this title, shall be treated as a single employer for purposes of this subparagraph.