scope:

Subpart B applies to multiemployer plans covered by title IV of ERISA, with respect to which there is a termination by the withdrawal of every employer (including a plan created by a partition pursuant to section 4233 of ERISA) or a withdrawal of substantially all employers in the plan pursuant to an agreement or arrangement to withdraw from the plan, and to employers that withdraw from such multiemployer plans. The obligations of a plan sponsor of a mass-withdrawalterminated plan under subpart B shall cease to apply when the plan assets are distributed in full satisfaction of all nonforfeitable benefits under the plan. Subpart B also applies, to the extent appropriate, to multiemployer plans with respect to which there is a withdrawal of substantially all employers in a single plan year and to employers that withdraw from such plans in that plan year.