CMS Pub. 100-05, ch. 2, § 30.2

The Medicare as secondary for the disabled provision applies only to LGHPs that cover

employees of at least one employer that employed 100 or more full-time and/or part-time

employees on 50 percent or more of its business days during the previous calendar year.

Medicare is secondary for all employees enrolled in the plan if a plan is a multi- employer

plan, such as a union plan which covers employees of some small employers and also

employees of at least one employer that meets the 100-or- more employee requirement,

including those that work for small employers. The exception discussed in this chapter,

with respect to the working aged provision, does not apply to the Medicare as secondary

for the disabled provision. An employer will be considered to employ 100 or more

employees on a particular day if the employer has at least 100 full-time or part-time

employees on his/her employment rolls on that day. This condition is met as long as the

total number of individuals on the employer's rolls adds up to at least 100 regardless of the

number of employees who work or who are expected to report for work on that day.

Self-employed individuals who participate in an LGHP are not counted as employees for

purposes of determining if the 100-or-more employee requirement is met. If an employer

does not meet the 100-or-more employees requirement in a particular year, the employer

may offer employees coverage that is secondary to Medicare during the following year.

If the employer meets the 100-or-more employee requirement at any time during the

current year, the employer is required to provide employees with coverage that is primary

to Medicare during the following year.