About one-fifth of all workers with traditional pension plans are covered by multi-employer, as opposed to single employer, plans. Multi-employer plans enable employees to gain credit towards a pension from work with several different employers. Portability and age-of-retirement provisions differ in these two types of plans.
Portability agreements with other plans apply to 60 percent of employees under multi-employer plans compared to 3 percent of those under single employer plans. These provisions allow participants to transfer years of credited service or accumulated benefits from one plan to another. Because multi-employer pension plans are typically found in industries characterized by workers who switch employers frequently (in some cases to employers not participating in the original multi-employer plan), a greater need exists for such portability of benefits.
Multi-employer plans are more likely than single-employer plans to provide normal (unreduced) retirement benefits for those retiring before age 65. In 1994-95, some 52 percent of employees in single-employer plans could not retire until age 65, compared with 33 percent of employees in multi-employer plans. Furthermore, some 39 percent of employees in multi-employer plans could retire at age 62, compared with only 23 percent of employees covered by single-employer plans.
Bureau of Labor Statistics, U.S. Department of Labor, The Economics Daily, Single- and multi-employer defined benefit pension plans differ at https://www.bls.gov/opub/ted/1999/apr/wk1/art03.htm (visited October 06, 2022).