With DB plans, participants receive regular monthly benefit payments in retirement (which some refer to as a "traditional" pension). The plans that are the subject of this report are DB plans. Multiemployer pension plans are sponsored by more than one employer (often, though not required to be, in the same industry) and maintained as part of a collective bargaining agreement. When a multiemployer pension plan becomes insolvent, the Pension Benefit Guaranty Corporation (PBGC) provides financial assistance to the plan so the plan can continue to pay benefits up to the PBGC guaranteed amount. This suggests that a larger percentage of participants in plans that receive PBGC financial assistance in the future are likely to see benefit reductions as a result of the PBGC maximum guarantee level. PBGC estimates that in the future it will not have sufficient resources from which to provide financial assistance for insolvent plans to pay benefits at the PBGC guarantee level. Multiemployer Pension Plan Data

CRS analyzed public-use Form 5500 data from the Department of Labor (DOL) for the 2015 plan year, the most recent year for which complete data are available. Most private-sector pension plans are required to annually report to the Internal Revenue Service (IRS), DOL, and PBGC information about the plan, such as the number of participants, financial information, and the companies that provide services to the plan. For example, most multiemployer DB plans are required to file Schedule MB, which contains information specific to multiemployer DB plans, such as the zone status of the plan (described below). Not all multiemployer DB pension plans file Schedule MB. 109-280 ) required that multiemployer plans that meet specified financial criteria must report to the IRS their financial condition as being in one of several categories. Multiemployer Plan Insolvencies by Year

As noted above, data from Schedule MB of Form 5500 for the 2015 plan year showed that 83 plans indicated that they were in critical and declining status and expected to become insolvent. The 25 Largest Multiemployer Plans

Plans with 75,000 or more participants, which were the 25 largest multiemployer DB pension plans (by the number of participants) in the 2015 plan year, are listed in Table 4 . For each plan, the table contains the number of participants, the zone status in 2015, the funded percentage, the amount of underfunding in the plan, and the amount of expected payments in the 2015 plan year. In total, these plans have 4.7 million participants, which is 44.4% of participants in multiemployer plans that filed Schedule MB in 2015. Schedule R, Part V, Line 13 of Form 5500 requires multiemployer DB plans to list employers that contribute more than 5% of that plan's total contributions (referred to in this report as "5% contributors"). Note that an employer's total contributions to all of the multiemployer plans to which it contributed could have been larger than the amount listed in Table 5 if the employer contributed to additional plans, but whose contributions to those other plans were less than 5% of a plan's total contributions. 5% Contributors in the Largest Critical and Declining Multiemployer DB Plans

 Table 6 lists the 5% contributors in the 12 largest multiemployer DB plans that are in critical and declining status (ranked by the amount of total contributions to the plan for the 2015 plan year) and the number of plans in which each employer is a 5% contributor.
Multiemployer defined benefit (DB) pension plans are pensions sponsored by more than one employer and maintained as part of a collective bargaining agreement. With DB pensions, participants receive a monthly benefit in retirement that is based on a formula. With multiemployer DB pensions, the formula typically multiplies a dollar amount by the number of years of service the employee has worked for employers that participate in the DB plan.
Some DB pension plans have sufficient resources from which to pay their promised benefits. But, as a result of a variety of factors—such as changes in the unionized workforce and the 2007 to 2009 recession—many multiemployer DB plans are likely to become insolvent over the next 20 years and run out of funds from which to pay benefits owed to participants.
The Pension Benefit Guaranty Corporation (PBGC) is a U.S. government agency that insures the benefits of participants in private-sector DB pension plans. Although PBGC is projected to have sufficient resources to provide financial assistance through 2025 to smaller multiemployer DB plans, the projected insolvency of large multiemployer DB pension plans would likely result in a substantial strain on PBGC's multiemployer insurance program. In a report released in June 2017, PBGC indicated that the multiemployer insurance program is highly likely to become insolvent by 2025. In the absence of increased financial resources for PBGC, participants in insolvent multiemployer DB pension plans would likely see sharp reductions in their pension benefits.
This report's data are from the public use file of the Form 5500 annual disclosure for the 2015 plan year (the most recent year for which complete information is available). Nearly all private-sector pension plans (including multiemployer DB plans) are required to file Form 5500 with the Internal Revenue Service (IRS), the Department of Labor (DOL), and PBGC. The Form 5500 information includes breakdowns on the number of plan participants, financial information about the plan, and details of companies providing services to the plan. Multiemployer DB plans specifically are required to report their financial condition as being in one of several categories (referred to as the plan's "zone status").
The insolvencies of these plans could affect the employers that contribute to multiemployer plans. For example, an employer in a plan that becomes insolvent plan might have to recognize the total amount of its future obligations to the plan, which could affect the employer's access to credit and, potentially, its participation in other multiemployer plans.
This report provides data on multiemployer DB plans categorized in several ways. First, the report categorizes the data based on plans' zone status in 2015. Next, it provides a year-by-year breakdown of the number of plans that are expected to become insolvent and the number of participants in those plans. It then provides information on the 25 largest multiemployer DB plans in 2015 (each plan has at least 75,000 participants). Finally, the report provides data on those employers whose plans indicate they contributed more than 5% of the plans' total contributions (referred to in this report as "5% contributors") in the 2015 plan year. It lists (1) the 5% contributors whose total contributions to multiemployer plans were at least $25 million and (2) the 5% contributors in the 12 largest multiemployer plans (as ranked by total contributions to the plan) that are in critical and declining status.