PUBLIC LAW 96-364—SEPT. 26, 1980
94 STAT. 1227
"(b)(1) Except as provided in subsections (c) and (d), the amount of unfunded vested benefits allocable to an employer that withdraws is the sum of— "(A) the employer's proportional share of the unamortized amount of the change in the plan's unfunded vested benefits for plan years ending after April 28, 1980, as determined under paragraph (2), "(B) the employer's proportional share, if any, of the unamortized amount of the plan's unfunded vested benefits at the end of the plan year ending before April 29, 1980, as determined under paragraph (3); and "(C) the employer's proportional share of the unamortized amounts of the reallocated unfunded vested benefits (if any) as determined under paragraph (4). If the sum of the amounts determined with respect to an employer under paragraphs (2), (3), and (4) is negative, the unfunded vested benefits allocable to the employer shall be zero. "(2)(A) An employer's proportional share of the unamortized amount of the change in the plan's unfunded vested benefits for plan years ending after April 28, 1980, is the sum of the employer's proportional shares of the unamortized amount of the change in unfunded vested benefits for each plan year in which the employer has an obligation to contribute under the plan ending— "(i) after such date, and "(ii) before the plan year in which the withdrawal of the employer occurs. "(B) The change in a plan's unfunded vested benefits for a plan year is the amount by which— "(i) the unfunded vested benefits at the end of the plan year; exceeds "(ii) the sum of— "(I) the unamortized amount of the unfunded vested benefits for the last plan year ending before April 29, 1980, and "(II) the sum of the unamortized amounts of the change in unfunded vested benefits for each plan year ending after April 28, 1980, and preceding the plan year for which the change is determined. "(C) The unamortized amount of the change in a plan's unfunded vested benefits with respect to a plan year is the change in unfunded vested benefits for the plan year, reduced by 5 percent of such change for each succeeding plan year. "(D) The unamortized amount of the unfunded vested benefits for the last plan year ending before April 29, 1980, is the amount of the unfunded vested benefits as of the end of that plan year reduced by 5 percent of such amount for each succeeding plan year. "(E) An employer's proportional share of the unamortized amount of a change in unfunded vested benefits is the product of— "(i) the unamortized amount of such change (as of the end of the plan year preceding the plan year in which the employer withdraws); multiplied by "(ii) a fraction— "(I) the numerator of which is the sum of the contributions required to be made under the plan by the employer for the year in which such change arose and for the 4 preceding plan years, and "(II) the denominator of which is the sum for the plan year in which such change arose and the 4 preceding plan years of all contributions made by employers who had an obligation
Allocation determination.
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