Free tool · federal
Public Support Test calculator
The IRS public support test (§509(a)(1) / §170(b)(1)(A)(vi)) decides whether your 501(c)(3) stays a public charity or tips into private-foundation status. Enter each large donor's cumulative giving across the rolling 5-year window: gifts from individuals and corporations count toward public support only up to 2% of total support, while grants from public charities and governmental units count in full. Pass line: 33⅓%.
Modeled as equal gifts. If the average gift exceeds the 2% cap, the pool is shaved accordingly — the count is what protects you.
Counts toward total support but not public support — leaving it out overstates your ratio, so include it.
| Total support (T) | $0.00 |
| 2% cap per donor | $0.00 |
| Public support (numerator) | $0.00 |
Enter support to solve.
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How the test works
Why does one big donor hurt the ratio?›
Each individual or corporate donor's giving counts toward the numerator only up to 2% of total support — but their full gift still lands in the denominator. A $250,000 gift to a $500,000 organization adds $250,000 to the bottom of the fraction and only $10,000 to the top. That asymmetry is why concentration, not generosity, is what fails the test.
Which money is never capped?›
Grants from governmental units and from other §509(a)(1)/§170(b)(1)(A)(vi) public charities count in full on both sides of the fraction. A community-foundation grant is structurally better for your ratio than the same dollars from the founder.
What if we're between 10% and 33⅓%?›
The facts-and-circumstances test can keep you a public charity at 10%+ — but the percentage is only the entry ticket. The IRS also weighs whether the organization is organized and operated to attract new public or governmental support: a real fundraising program, a broad board, services aimed at the public.
Why do small gifts matter so much?›
Dollars under the 2% cap count in full. The “gap to pass” panel above solves for the smallest amount of additional under-cap giving that reaches 33⅓% — and the minimum numberof gifts, because fewer, larger gifts get shaved by the cap and don't close the gap.
When does this actually bite?›
Schedule A, Part II of your Form 990, every year, over a rolling 5-year window. New organizations get a grace period through their first five tax years; after that, two consecutive failing years reclassify you as a private foundation — with excise taxes, tighter grant rules, and donors' deduction limits shrinking.
One test of many
Public support is one federal test. State charity registration is fifty more.
Most states require charities to register before soliciting donations — each with its own registry, renewal date, and fee schedule. See where your organization stands in every state we track, free, from the same public records regulators publish.
Run your free registration scan →Planning model, not tax advice — it mirrors Schedule A, Part II mechanics but simplifies the small-donor pool (modeled as equal gifts) and omits unusual-grant exclusions. Include investment income and membership fees under “other support” or your ratio will read high. Confirm with your accountant or counsel before relying on it for a filing. See our disclaimer.