
Section 509(a) Public Support Test: How Nonprofits Stay Public Charities
The Section 509(a) public support test requires 501(c)(3) nonprofits to draw more than one-third of support from the public over a rolling five-year window. Fail it twice and you tip into private foundation status—facing a 1.39% excise tax on investment income, mandatory 5% annual payout, and donor deduction limits that drop from 60% to 30% of AGI.










