From IRS Publication 557, Tax-Exempt Status for Your Organization

From IRS Publication 557, Tax-Exempt Status for Your Organization
Chapter 3 - Section 501(c)(3) Organizations, Introduction
An organization may qualify for exemption from federal income tax if it is organized and operated exclusively for one or more of the following purposes:

Charitable,
Religious,
Educational,
Scientific,
Literary,
Testing for public safety,
Fostering national or international amateur sports competition (but only if none of its activities involve providing athletic facilities or equipment; however, see Amateur Athletic Organizations, later in this chapter), or
The prevention of cruelty to children or animals.

To qualify, the organization must be a corporation, community chest, fund, or foundation. A trust is a fund or foundation and will qualify. However, an individual or a partnership will not qualify.

Examples. Qualifying organizations include:

Nonprofit old age homes,
Parent-teacher associations,
Charitable hospitals or other charitable organizations,
Alumni associations,
Schools,
Chapters of the Red Cross or Salvation Army,
Boys' clubs, and
Churches.

Child care organizations. The term "educational purposes" includes the providing of care of children away from their homes if substantially all the care provided is to enable individuals (the parents) to be gainfully employed and the services are available to the general public.

Instrumentalities. A state or municipal instrumentality may qualify under section 501(c)(3) if it is organized as a separate entity from the governmental unit that created it and if it otherwise meets the organizational and operational tests of section 501(c)(3). Examples of a qualifying instrumentality might include state schools, universities, or hospitals. However, if an organization is an integral part of the local government or possesses governmental powers, it does not qualify for exemption. A state or municipality itself does not qualify for exemption.

Source:
IRS Publication 557, Chapter 3