How the 509(a)(1) calculation works
Section 509(a)(1), together with section 170(b)(1)(A)(vi), generally fits organizations supported by gifts, grants, and contributions from public sources. Program-service receipts are not included in this contribution total. Under the simplified Form 1023-EZ calculation, qualifying public support of at least 33 1/3% meets the main test.
Large private donations receive limited credit
For this calculation, a private donor's gifts count as public support only up to 2% of the organization's total gifts, grants, and contributions. Contributions from governmental units and public charities receive different treatment.
A result between 10% and 33 1/3% needs review
A result in this range does not automatically fail Line 2a. The IRS may consider continuing efforts to attract public support and other signs that the organization operates as a publicly supported charity.