29 U.S.C. § 1382. Determination and collection of liability; notification of employer

When an employer withdraws from a multiemployer plan, the plan sponsor, in accordance with this part, shall—

1. (1)
   (1)determine the amount of the employer’s withdrawal liability,
2. (2)
   (2)notify the employer of the amount of the withdrawal liability, and
3. (3)
   (3)collect the amount of the withdrawal liability from the employer.