How to read the result
- 33⅓% or more — you meet the public support test as a 509(a)(1) / 170(b)(1)(A)(vi) public charity.
- 10% to 33⅓% — you may still qualify under the facts-and-circumstances test if you can show you genuinely operate to attract public support.
- Under 10% — you fail this test and risk private-foundation status; ask a CPA about the 509(a)(2) test or restructuring your support.
Simplified estimator for the 509(a)(1) test. The real Schedule A calculation caps each individual/corporate donor’s gifts at 2% of total support (government units and other public charities are not capped), excludes “unusual grants,” and uses a five-year window. A separate 509(a)(2) test applies to organizations funded mainly by exempt-function (program) revenue. Confirm with a nonprofit CPA.
A funding base that widens your public support
Passing the public support test means money from many members of the public, not a few big donors. Good Circles builds exactly that kind of broad base — lots of supporters each contributing a share of their everyday local spending (about 10% of each merchant’s net profit; conservatively ~$72 per active supporter per year, an estimate), free for your nonprofit. Broad public support is good for your mission and for your 509(a)(1) math.
Claim a Founding Nonprofit spot →Sources & tools
Free first
- IRS Schedule A (Form 990) & instructions — the official public support test calculation and worksheets.
- IRS — public charities — how the IRS classifies public charities vs. private foundations.
- National Council of Nonprofits — plain-language guidance on maintaining public-charity status.
Paid — optional labor-savers
- A nonprofit CPA — computes Schedule A correctly and plans to keep you above the threshold. Worth it when your public support percentage is trending toward 33⅓% or below.
Last verified 2026-06-17. Figures and rules change — verify at the source before you act.
FAQ
What is the public support test?
It is the IRS test that determines whether a 501(c)(3) is a publicly supported charity rather than a private foundation. Under section 509(a)(1) and 170(b)(1)(A)(vi), an organization generally must receive at least one-third of its total support from the general public and government over a five-year measuring period.
What is the 2% donor cap?
When computing public support under the 509(a)(1) test, the amount counted from any one individual or company is limited to 2% of the organization’s total support over the period. Contributions from government units and other public charities are not subject to this cap. The cap prevents a few very large gifts from masking a narrow base.
What happens if we fail the test?
An organization that cannot meet the one-third test or the 10% facts-and-circumstances test is reclassified as a private foundation, which brings stricter rules, excise taxes, and different deductibility limits. Many organizations instead qualify under the alternative 509(a)(2) test if they earn significant exempt-function revenue.
Is this calculator the official figure?
No. This is a simplified planning estimate. The official public support percentage is calculated on Schedule A of the Form 990 with the donor cap, unusual-grant exclusions, and the five-year window applied. Use this to monitor your position, then confirm with a CPA.