29 CFR § 4219.12 - Employers liable upon mass withdrawal.
(a) Liability for de minimis amounts. An employer shall be liable for de minimis amounts to the extent provided in section 4219(c)(1)(D) of ERISA if the employer's initial withdrawal liability was reduced pursuant to section 4209 (a) or (b) of ERISA.
(c) Liability for reallocation liability. An employer shall be liable for reallocation liability if the employer withdrew pursuant to an agreement or arrangement to withdraw from a multiemployer plan from which substantially all employers withdrew pursuant to an agreement or arrangement to withdraw, or if the employer withdrew after the beginning of the second full plan year preceding the termination date from a plan that terminated by the withdrawal of every employer, and, as of the reallocation record date -
(1) The employer has not been completely liquidated or dissolved;
(2) The employer is not the subject of a case or proceeding under title 11, United States Code, or any case or proceeding under similar provisions of state insolvency laws, except that a plan sponsor may determine that such an employer is liable for reallocation liability if the plan sponsor determines that the employer is reasonably expected to be able to pay its initial withdrawal liability and its redetermination liability in full and on time to the plan; and
(d) General exclusion. In the event that a plan experiences successive mass withdrawals, an employer that has been determined to be liable under this subpart for any component of mass withdrawal liability shall not be liable as a result of the same withdrawal for that component of mass withdrawal liability with respect to a subsequent mass withdrawal.
(e) Free-look rule. An employer that is not liable for initial withdrawal liability pursuant to a plan amendment adopting section 4210(a) of ERISA shall not be liable for de minimis amounts or for 20-year-limitation amounts, but shall be liable for reallocation liability in accordance with paragraph (c) of this section.
(f) Payment of initial withdrawal liability. An employer's payment of its total initial withdrawal liability, whether by prepayment or otherwise, for a withdrawal which is later determined to be part of a mass withdrawal shall not exclude the employer from or otherwise limit the employer's mass withdrawal liability under this subpart.
(g) Agreement presumed. Withdrawal by an employer during a period of three consecutive plan years within which substantially all employers withdraw from a plan shall be presumed to be a withdrawal pursuant to an agreement or arrangement to withdraw unless the employer proves otherwise by a preponderance of the evidence.