A subordinate organization is one that is under control of the central organization.
According to the United States IRS Publication 557 (Rev. Oct. 2010), Tax-Exempt Status for Your Organization this is the definition for a subordinate organization:
"A subordinate organization is a chapter, local, post or unit of a central organization. A central organization may be a subordinate itself, such as a state organization that has subordinate units and is itself affiliated with a national (central) organization."
A subordinate organization may or may not be incorporated, but it must have an organizing document. A subordinate that is organized and operated in a foreign country may not be included in a Group Exemption Letter (GEL). A subordinate described in section 501(c)(3) may not be included in a group exemption letter if it is a private foundation described in section 509(c).
Advice
If an organization is a subordinate one controlled by a central organization (for example, a church, the Boy Scouts, or a fraternal organization), it is necessary to check with the central organization to ensure it has been issued a GEL that covers the organization. If it has, you do not have to file a separate application unless your organization no longer wants to be included in the group exemption letter.
If a group exemption letter does not cover your organization, ask your central organization about being included in the next annual group ruling update that it submits to the IRS.