Medicare Secondary Payer Manual (Pub. 100-05), Ch. 2 § 10.6
Aggregation Rules Applicable to Determine the Employer Size
10.6 - Aggregation Rules Applicable to Determine the Employer Size
(Rev. 11755, Issued:12-21-2022, Effective: 01-23-2023, Implementation: 01-23-23)
The size of the employer is a factor in determining whether Medicare is secondary or
primary payer under the working aged and disability provisions of the law. For MSP
purposes, the employer is the legal entity that employs the employees. For example, the
employer may be an individual, a partnership, or a corporation. Ordinarily, the identity
of that entity is clear.
There are situations, however, when it is not clear which corporation or individual is the
employing entity for MSP purposes. For example, when a corporation is owned or
controlled by another corporation, it must be decided which corporation is the employer.
Similarly, when related individuals each have businesses and each claim to be a separate
employer with either fewer than 20 or fewer than 100 employees, it must be decided
whether the individuals are separate employers or a single employer.
The MSP law contains the following rules for determining the size of the employer under
the MSP for the aged and disabled provisions. [See 42 CFR § 411.106]
A. Single Employers
Single employers under Section §52 of the IRC are defined as follows:
• All employers that are treated as single employers under subsections (a) or (b) of
§52 of the IRC are treated as single employers;
• Section 52(a) of the IRC provides that all employees of all corporations that are
members of the same controlled group of corporations are treated as if employed by a
single employer; and,
• Section 52(b) of the IRC provides that all employees of trades or businesses
(whether or not incorporated), e.g., employees of partnerships or proprietorships that are
under common control, shall be treated as employed by a single employer.
In general, two or more individuals or corporations are considered to be separate
employers under §52(a) or (b) of the IRC if they file separate income tax returns. Two or
more individuals are considered to be a single employer if they file a consolidated tax
return.
When there is a question about the tax status of a particular employer that claims to have
fewer employees than the 20 or 100 employee thresholds, A/B MACs and DME MACs
must request the employer to submit copies of its most recent tax return to resolve the
question.
B. Affiliated Service Groups
All employees of the members of an affiliated service group (as defined in Section
414(m) of the IRC) are treated as employed by a single employer.
C. Treatment of Religious Organizations
CMS does not aggregate religious organizations for MSP purposes. Incorporated
parishes and churches that are part of a church-wide organization, such as a diocese or
synod, are considered to be individual employers. A GHP or LGHP for employees of
such parishes or churches is considered to be a multi-employer GHP. (See
§10.3 and §10.4 of this chapter, for policies regarding multi-employer GHPs in
which at least one participating employer employs 20 or 100 or more employees
respectively.)