Treas. Reg. § 1.414(f)-1 — Definition of multiemployer plan.

(a) General rule. For purposes of part I of subchapter D of chapter 1 of the Code and the regulations thereunder, a plan is a multiemployer plan for a plan year if all of the following requirements are satisfied:

(1) Number of contributing employers. More than one employer is required by the plan instrument or other agreement to contribute (or to have contributions made on its behalf) to the plan for the plan year.

(2) Collective bargaining agreement. The plan is maintained for the plan year pursuant to one or more collective bargaining agreements between employee representatives and more than one employer.

(3) Amount of contributions. Except as provided by paragraph (c) of this section (relating to the special rule for contributions exceeding 50 percent), the amount of contributions made under the plan for the plan year by or on behalf of each employer is less than 50 percent of the total amount of contributions made under the plan for such plan year by or on behalf of all employers.

(4) Benefits. The plan provides that the amount of benefits payable with respect to each employee participating in the plan is determined without regard to whether or not his employer continues as a member of the plan. If benefits accrued as a result of the participant's service with his employer during a period before such employer was a member of the plan, this requirement does not apply to the amount of those benefits, except that this requirement does apply to the amount of those benefits (i) which are accrued benefits derived from employee contributions, or (ii) which are accrued under a plan maintained by an employer prior to the time such employer became a member of the plan to which the requirements of this paragraph (a) are applied.

(5) Other requirements. The plan satisfies such other requirements as the Secretary of Labor by regulations prescribes under the authority of section 414(f)(1)(E) of the Code and section 3(37) of the Employee Retirement Income Security Act of 1974 (Pub. L. 93-406, 88 Stat. 839). See 29 CFR 2510.3-37.

(b) Special rules

(1) Amount of contributions. For purposes of paragraphs (a)(3) and (c) of this section, the amount of contributions made under the plan for the plan year by or on behalf of each employer shall be the sum of such contributions made on or before the last day of the plan year. For purposes of determining whether contributions are made on or before the last day of the plan year, the rule of section 412(c)(10) and the regulations thereunder (relating to the treatment of certain contributions made after the last day of the plan year as made on such last day) shall apply.

(2) Benefits.

(i) For purposes of paragraph (a)(4) of this section, certain benefit amounts are treated as accrued as a result of the participant's service with an employer during a period before such employer was a member of the plan. The amount of such a benefit so treated is the difference (if any) between two calculated amounts. The first calculated amount is the participant's total accrued benefit calculated under the plan as of the date the employer ceased to be a member of the plan. The second calculated amount is the participant's accrued benefit calculated without regard to his service with such employer during the period before such employer was a member of the plan. However, under a special limitation, this difference may not exceed the benefit a participant accrued from service before his employer became a member of the plan. For purposes of this limitation, this benefit is the benefit accrued as of the date the employer ceases to be a member of the plan. An employer shall be deemed to be a member of the plan in a plan year if the employer is required by the plan instrument or other agreement to contribute (or to have contributions made on its behalf) to the plan for such plan year or if an employee of the employer accrues a benefit, on account of service with the employer during such plan year, under the plan for that plan year.

(ii) The provisions of paragraphs (a)(4) and (b)(2)(i) of this section are illustrated by the following example:

Example.
On January 1, 1976, employer W became a member of the noncontributory XYZ pension plan which uses the calendar year as the plan year. W did not maintain any plan prior to that date. The plan provided for benefits of $4 per month per year of service (including service with W before January 1, 1976). On January 1, 1980, following adoption of a new collective bargaining agreement, the benefits were increased to $12 per month per year of service for all years of service (including service with W before January 1, 1976). On January 1, 1991, W ceased to be a member of the plan.
A, an employee of W, had 15 years of service before January 1, 1976, 4 years of service between January 1, 1976, and December 31, 1979, and 11 years of service between January 1, 1980, and December 31, 1990. On December 31, 1990, A's accrued benefit was $360 per month ($12 per month x 30). On January 1, 1991, the portion of A's accrued benefit retained and the portion forfeited under the terms of the XYZ pension plan were determined as follows:
Years Monthly accrued benefit retained Monthly accrued benefit forfeited
Before Jan. 1, 1976 $12×15 years=$180
Jan. 1, 1976 to Dec. 31, 1979 $4×4 years=$16 $8×4 years=$32
Jan. 1, 1980 to Dec. 31, 1990 $12×11 years=$132
Total $148 $212
The XYZ plan does not satisfy the requirements of paragraphs (a)(4) and (b)(2)(i) of this section because no benefit can be forfeited with respect to service after W began participating in the plan. Thus, the maximum accrued benefit that may be forfeited is $180 per month (the accrued benefit with respect to A's service prior to January 1, 1976). Therefore, in order for the plan to meet the requirements of paragraphs (a)(4) and (b)(2)(i) of this section, the plan must provide for A's accrued benefit after W ceased to be a member of the plan to be at least $180 per month ($360 per month total accrued benefit less $180 per month benefit accrued for service prior to W's membership in the plan).

Years	Monthly accrued benefit retained	Monthly accrued benefit forfeited
Before Jan. 1, 1976		$12×15 years=$180
Jan. 1, 1976 to Dec. 31, 1979	$4×4 years=$16	$8×4 years=$32
Jan. 1, 1980 to Dec. 31, 1990	$12×11 years=$132
Total	$148	$212

(iii) For purposes of paragraphs (a)(4) and (b)(2) of this section, if an employer for a period employs two or more individuals who, solely by reason of their employment, are participants in the plan and who do not belong to the same collective bargaining unit, the dates on which the employer became and ceased to be a member of the plan shall be determined separately on a class basis for individuals who belong to separate collective bargaining units, as separate classes, and for individuals who do not belong to a collective bargaining unit, as a further single separate class. Thus, such dates shall be determined with respect to individuals as a class who belong to the same collective bargaining unit (or who do not belong to a collective bargaining unit) without consideration of the employment by the employer of, or the participation in the plan by, other individuals (who do not belong to such collective bargaining unit and who may belong to another collective bargaining unit) or whether the employer is a member of the plan with respect to such other individuals. In no event, however, may service not attributable to service with a particular collective bargaining unit be disregarded under paragaphs (a)(4) and (b)(2) of this section merely because the employer ceases to maintain the plan with respect to such unit. Thus, for example, paragraphs (a)(4) and (b)(2) of this section do not permit the disregard of a period of service of an individual belonging to a collective bargaining unit prior to the time the employer became a member of the plan with respect to such unit to the extent that, during such period of service, the individual belonged to another collective bargaining unit with respect to which the employer was a member of the plan.

(3) Controlled groups. For purposes of section 414(f) and this section, all corporations which are members of a controlled group of corporations (within the meaning of section 1563(a) and the regulations thereunder, but determined without regard to section 1563(e)(3)(C) and the regulations thereunder) are deemed to be one employer.

(c) Contributions exceeding 50 percent. If a plan was a multiemployer plan as defined in this section for any plan year (including plan years ending prior to September 3, 1974), “75 percent” shall be substituted for “50 percent” in applying paragraph (a)(3) of this section for subsequent plan years until the first plan year following a plan year in which the amount contributed by or on behalf of one employer is 75 percent or more of the total amount of contributions made under the plan for that plan year by or on behalf of all of the employers making contributions. In such case “75 percent” shall not again be substituted for “50 percent” until the plan has met the requirements of paragraph (a) of this section (determined without regard to this paragraph) for one plan year.

(d) Examples. The application of this section is illustrated by the following examples. For purposes of these examples, assume that the plan meets the requirements of paragraphs (a) (1), (2), (4), and (5) of this section for each plan year.

Example (1).
On January 1, 1970, U, V, and W, three employers none of which is a member of a controlled group of corporations with any of the other two employers, establish a plan with a plan year corresponding to the calendar year. U, V, and W each contribute less than one-half of the total contributions made under the plan for each of the years 1970, 1971, and 1972. For the years 1973, 1974, and 1975, U contributes 70 percent and V and W each contribute 15 percent of the total contributions made under the plan for each year. The plan is a multiemployer plan under section 414(f) and this section for 1975 because no employer has contributed 75 percent or more of the total amount contributed for each of the plan years subsequent to 1972.

Example (2).
(i) First plan year. On January 1, 1975, X, Y, and Z, three employers none of which is a member of a controlled group of corporations with any of the other two employers, establish a plan with a plan year corresponding to the calendar year. X, Y, and Z each contribute less than one-half of the total contributions made under the plan for 1975. The plan is a multiemployer plan for 1975 because it meets the 50 percent contribution requirement of paragraph (a)(3) of this section.
(ii) Second plan year. For the second plan year, 1976, X contributes 70 percent and Y and Z each contribute 15 percent of the total contributions made under the plan. The plan is a multiemployer plan for 1976 because it was a multiemployer plan for the preceding plan year and satisfies the 75 percent contribution requirement of paragraph (c) of this section.
(iii) Third plan year. For the third plan year, 1977, X contributes 80 percent and Y and Z each contribute 10 percent of the total contributions made under the plan. The plan is not a multiemployer plan for 1977 because it fails to satisfy the 75 percent contribution requirement of paragraph (c) of this section.
(iv) Fourth plan year. For the fourth plan year, 1978, Y contributes 60 percent and X and Z each contribute 20 percent of the total contributions made under the plan. The 75 percent contribution requirement of paragraph (c) of this section does not apply. The plan is not a multiemployer plan for 1978 because it fails to satisfy the 50 percent contribution requirement of paragraph (a)(3) of this section.
(v) Fifth plan year. For the fifth plan year, 1979, X, Y, and Z each contribute less than one-half of the total contributions made under the plan. The 75 percent contribution requirement of paragraph (c) of this section does not apply. The plan is a multiemployer plan for 1979 because it again meets the 50 percent contribution requirement of paragraph (a)(3) of this section.
(vi) Sixth plan year. For the sixth plan year, 1980, the plan will continue to be a multiemployer plan, provided that no employer contributes 75 percent or more of the total amount of contributions made under the plan for the plan year.