(a) Purpose. The purpose of this part is to prescribe rules, pursuant to section 4206(b) of ERISA, for adjusting the partial or complete withdrawal liability of an employer that previously partially withdrew from the same multiemployer plan. Section 4206(b)(1) provides that when an employer that has partially withdrawn from a plan subsequently incurs liability for another partial or a complete withdrawal from that plan, the employer's liability for the subsequent withdrawal is to be reduced by the amount of its liability for the prior partial withdrawal (less any waiver or reduction of that prior liability). Section 4206(b)(2) requires the PBGC to prescribe regulations adjusting the amount of this credit to ensure that the liability for the subsequent withdrawal properly reflects the employer's share of liability with respect to the plan. The purpose of the credit is to protect a withdrawing employer from being charged twice for the same unfunded vested benefits of the plan. The reduction in the credit protects the other employers in the plan from becoming responsible for unfunded vested benefits properly allocable to the withdrawing employer. In the interests of simplicity, the rules in this part provide for, generally, a one-step calculation of the adjusted credit under section 4206(b)(2) against the subsequent liability, rather than for separate calculations first of the credit under section 4206(b)(1) and then of the reduction in the credit under paragraph (b)(2) of that section. In cases where the withdrawal liability for the prior partial withdrawal was reduced by an abatement or other reduction of that liability, the adjusted credit is further reduced in accordance with § 4206.8 of this part.

(b) Scope. This part applies to multiemployer plans covered under title IV of ERISA, and to employers that have partially withdrawn from such plans after September 25, 1980 and subsequently completely or partially withdraw from the same plan.

The following are defined in § 4001.2 of this chapter: Code, employer, ERISA, multiemployer plan, PBGC, plan, and plan year.

In addition, for purposes of this part:

Complete withdrawal means a complete withdrawal as described in section 4203 of ERISA.

Partial withdrawal means a partial withdrawal as described in section 4205 of ERISA.

Unfunded vested benefits means, as described in section 4213(c) of ERISA, the amount by which the value of nonforfeitable benefits under the plan exceeds the value of the assets of the plan.

Whenever an employer that was assessed withdrawal liability for a partial withdrawal from a plan partially or completely withdraws from that plan in a subsequent plan year, it shall receive a credit against the new withdrawal liability in an amount greater than or equal to zero, determined in accordance with this part. If the credit determined under §§ 4206.4 through 4206.9 is less than zero, the amount of the credit shall equal zero.

(a) General. In a plan that uses the presumptive allocation method described in section 4211(b) of ERISA, the credit shall equal the sum of the unamortized old liabilities determined under paragraph (b) of this section, multiplied by the fractions described or determined under paragraph (c) of this section. When an employer's prior partial withdrawal liability has been reduced or waived, this credit shall be adjusted in accordance with § 4206.8.

(b) Unamortized old liabilities. The amounts determined under this paragraph are the employer's proportional shares, if any, of the unamortized amounts as of the end of the plan year preceding the withdrawal for which the credit is being calculated, of—

(1) The plan's unfunded vested benefits as of the end of the last plan year ending before September 26, 1980;

(2) The annual changes in the plan's unfunded vested benefits for plan years ending after September 25, 1980, and before the year of the prior partial withdrawal; and

(3) The reallocated unfunded vested benefits (if any), as determined under section 4211(b)(4) of ERISA, for plan years ending before the year of the prior partial withdrawal.

(c) Employer's allocable share of old liabilities. The sum of the amounts determined under paragraph (b) are multiplied by the two fractions described in this paragraph in order to determine the amount of the old liabilities that was previously assessed against the employer.

(1) The first fraction is the fraction determined under section 4206(a)(2) of ERISA for the prior partial withdrawal.

(2) The second fraction is a fraction, the numerator of which is the amount of the liability assessed against the employer for the prior partial withdrawal, and the denominator of which is the product of—

(i) The amount of unfunded vested benefits allocable to the employer as if it had completely withdrawn as of the date of the prior partial withdrawal (determined without regard to any adjustments), multiplied by—

(ii) The fraction determined under section 4206(a)(2) of ERISA for the prior partial withdrawal.

(a) General. In a plan that uses the modified presumptive method described in section 4211(c)(2) of ERISA, the credit shall equal the sum of the unamortized old liabilities determined under paragraph (b) of this section, multiplied by the fractions described or determined under paragraph (c) of this section. When an employer's prior partial withdrawal liability has been reduced or waived, this credit shall be adjusted in accordance with § 4206.8.

(b) Unamortized old liabilities. The amounts described in this paragraph shall be determined as of the end of the plan year preceding the withdrawal for which the credit is being calculated, and are the employer's proportional shares, if any, of—

(1) The plan's unfunded vested benefits as of the end of the last plan year ending before September 26, 1980, reduced as if those obligations were being fully amortized in level annual installments over 15 years beginning with the first plan year ending on or after such date; and

(2) The aggregate post-1980 change amount determined under section 4211(c)(2)(C) of ERISA as if the employer had completely withdrawn in the year of the prior partial withdrawal, reduced as if those obligations were being fully amortized in level annual installments over the 5-year period beginning with the plan year in which the prior partial withdrawal occurred.

(c) Employer's allocable share of old liabilities. The sum of the amounts determined under paragraph (b) are multiplied by the two fractions described in this paragraph in order to determine the amount of old liabilities that was previously assessed against the employer.

(1) The first fraction is the fraction determined under section 4206(a)(2) of ERISA for the prior partial withdrawal.

(2) The second fraction is a fraction, the numerator of which is the amount of the liability assessed against the employer for the prior partial withdrawal, and the denominator of which is the product of—

(i) The amount of unfunded vested benefits allocable to the employer as if it had completely withdrawn as of the date of the prior partial withdrawal (determined without regard to any adjustments), multiplied by—

(ii) The fraction determined under section 4206(a)(2) of ERISA for the prior partial withdrawal.

In a plan that uses the rolling-5 allocation method described in section 4211(c)(3) of ERISA, the credit shall equal the amount of the liability assessed for the prior partial withdrawal, reduced as if that amount was being fully amortized in level annual installments over the 5-year period beginning with the plan year in which the prior partial withdrawal occurred. When an employer's prior partial withdrawal liability has been reduced or waived, this credit shall be adjusted in accordance with § 4206.8.

In a plan that uses the direct attribution allocation method described in section 4211(c)(4) of ERISA, the credit shall equal the amount of the liability assessed for the prior partial withdrawal, reduced as if that amount was being fully amortized in level annual installments beginning with the plan year in which the prior partial withdrawal occurred, over the greater of 10 years or the amortization period for the resulting base when the combined charge base and the combined credit base are offset under section 431(b)(5) of the Code. When an employer's prior partial withdrawal liability has been reduced or waived, this credit shall be adjusted in accordance with § 4206.8.

(a) General. If an employer's withdrawal liability for a prior partial withdrawal has been reduced or waived, the credit determined pursuant to §§ 4206.4 through 4206.7 shall be adjusted in accordance with this section.

(b) Computation. The adjusted credit is calculated by multiplying the credit determined under the preceding sections of this part by a fraction—

(1) The numerator of which is the excess of the total partial withdrawal liability of the employer for all partial withdrawals in prior years (excluding those partial withdrawals for which the credit is zero) over the present value of each abatement or other reduction of that prior withdrawal liability calculated as of the date on which that prior partial withdrawal liability was determined; and

(2) The denominator of which is the total partial withdrawal liability of the employer for all partial withdrawals in prior years (excluding those partial withdrawals for which the credit is zero).

A plan that has adopted an alternative method of allocating unfunded vested benefits pursuant to section 4211(c)(5) of ERISA and part 4211 of this chapter shall adopt, by plan amendment, a method of calculating the credit provided by § 4206.3 that is consistent with the rules in §§ 4206.4 through 4206.8 for plans using the statutory allocation method most similar to the plan's alternative allocation method.

For the purposes of applying the rules in §§ 4206.4 through 4206.9 in any case in which either the prior or subsequent partial withdrawal resulted from a 70-percent contribution decline (or a 35-percent decline in the case of certain retail food industry plans), the first year of the 3-year testing period shall be deemed to be the plan year in which the partial withdrawal occurred.