(a) Error in direct attribution method. The unfunded vested benefits allocated to a withdrawing employer under the direct attribution method are the sum of the employer's attributable liability, determined under section 4211(c)(4)(A)(i) and (B) of ERISA, and the employer's share of the plan's unattributable liability, determined under section 4211(c)(4)(E) and allocated to the employer under section 4211(c)(4)(F). Plan sponsors should allocate unattributable liabilities on the basis of the employer's share of the attributable liabilities. However, section 4211(c)(4)(F) of ERISA, which describes the allocation of unattributable liabilities, contains a typographical error. Therefore, plans adopting the direct attribution method must modify the phrase “as the amount determined under subparagraph (C) for the employer bears to the sum of the amounts determined under subparagraph (C) for all employers under the plan” in section 4211(c)(4)(F) by substituting “subparagraph (B)” for “subparagraph (C)” in both places it appears.

(b) Allocating unattributable liability based on contributions in period before withdrawal. A plan that is amended to adopt the direct attribution method may provide that instead of allocating the unattributable liability in accordance with section 4211(c)(4)(F) of ERISA, the employer's share of the plan's unattributable liability is determined by multiplying the plan's unattributable liability determined under section 4211(c)(4)(E) by a fraction—

(1) The numerator of which is the total amount of contributions required to be made by the withdrawing employer over a period of consecutive plan years (not fewer than five) ending before the withdrawal; and

(2) The denominator of which is the total amount contributed under the plan by all employers for the same period of years used in paragraph (b)(1) of this section, decreased by any amount contributed by an employer that withdrew from the plan during those plan years.