What are 50% limit organizations?

You can ask any organization whether it's a qualified organization, and most will be able to tell you. You can also search for names of qualified organizations on the IRS's Tax Exempt Organization Search Tool .

50% limit organizations include the following:

1. Churches and conventions or associations of churches.
2. Educational organizations with a regular faculty and curriculum that normally have a regularly enrolled student body attending classes on site.
3. Hospitals and certain medical research organizations associated with these hospitals.
4. Organizations that are operated only to receive, hold, invest, and administer property and to make expenditures to or for the benefit of state and municipal colleges and universities and that normally receive substantial support from the United States or any state or their political subdivisions, or from the general public.
5. The United States or any state, the District of Columbia, a U.S. possession (including Puerto Rico), a political subdivision of a state or U.S. possession, or an Indian tribal government or any of its subdivisions that perform substantial government functions.
6. Certain publicly supported charities.
7. Organizations that may not qualify as "publicly supported" but that meet other tests showing they respond to the needs of the general public, not a limited number of donors or other persons. They must normally receive more than one-third of their support either from organizations described in (1) through (6), or from persons other than "disqualified persons".
8. Most organizations operated or controlled by, and operating for the benefit of, those organizations described in (1) through (7).
9. Private operating foundations.
10. Private nonoperating foundations that make qualifying distributions of 100% of contributions within 2 1/2 months following the year they receive the contributions. A deduction for charitable contributions to any of these private nonoperating foundations must be supported by evidence from the foundation confirming it made the qualifying distributions timely. Attach a copy of this supporting data to your tax return.
11. A private foundation whose contributions are pooled into a common fund, if the foundation would be described in (8) but for the right of substantial contributors to name the public charities that receive contributions from the fund. The foundation must distribute the common fund's income within 2 1/2 months following the tax year in which it was realized and must distribute the corpus not later than 1 year after the donor's death (or after the death of the donor's surviving spouse if the spouse can name the recipients of the corpus).