Unrelated business income

When the exemption stops

A 501(c)(3) — or any other exempt organisation — pays federal income tax on net income from a trade or business that is regularly carried on and not substantially related to its exempt purpose. All three conditions have to be met before the IRS treats the income as unrelated business income (UBI) ↗, which is then taxed at the standard corporate rate. Remove any one of them and the income stays exempt.

"Substantially related" is where most disputes live. A museum's café is regularly carried on and looks like a trade — but the IRS generally accepts that feeding visitors serves the educational mission. A university bookstore selling branded merchandise to the general public is harder to defend. The activity's relationship to the purpose, not just to the organisation, is what matters.

Several categories are expressly excluded from UBI by statute: dividends, interest, royalties, and most passive rents fall outside the definition regardless of how large they grow. So does income from volunteer-run activities and from the sale of donated goods — both explicit statutory exceptions under Internal Revenue Code section 512 ↗. Knowing the exclusions is as important as knowing the rule.

Organisations that have UBI report it on Form 990-T ↗, which is a separate return filed alongside the annual 990. The National Council of Nonprofits notes that an organisation with consistently large UBI relative to its exempt activities risks IRS scrutiny of the exemption itself — not just the tax bill. At that point the question shifts from how much tax is owed to whether the organisation is still principally operating for its stated purpose.

State income taxes may follow federal treatment, but each state sets its own rules, and several do not conform precisely to the federal UBI definition. An organisation with significant unrelated revenue should track both tracks.