Tax-exempt does not mean every dollar a nonprofit earns is tax-free. When a nonprofit runs a commercial activity that is not substantially related to its charitable mission, the income from that activity can be taxable — even though the organization itself remains exempt. This is the unrelated business income tax, and it catches more nonprofits off guard than any other filing requirement.
This is general information, not individual tax advice — the right treatment depends on your specific situation.
What Makes Income "Unrelated"
The IRS applies a three-part test: the income must come from a trade or business, it must be regularly carried on, and it must not be substantially related to the organization’s exempt purpose. All three conditions have to be true. A hospital gift shop that sells to the general public, a nonprofit that rents out office space it does not need, or a charity running a for-profit consulting practice can all generate unrelated business income even while every dollar raised goes toward the mission.
The $1,000 Filing Threshold
Any organization with $1,000 or more of gross unrelated business income in a fiscal year must file Form 990-T and pay tax on the net amount, generally at corporate tax rates. That threshold applies to gross income, not profit — a small, recurring commercial activity can trigger a filing requirement even if it barely breaks even. A specific deduction of $1,000 is allowed in computing the taxable amount, but the filing obligation itself kicks in well before that.
What Stays Tax-Free: The Key Exceptions
Several categories of income are excluded from UBIT even when they come from what looks like a business activity. Passive income — dividends, interest, most royalties, and many types of rental income — is generally excluded, since the organization is not actively running a trade or business to earn it. Qualified corporate sponsorship payments, where a sponsor receives simple acknowledgment rather than advertising, are excluded as well.
The Volunteer, Donated-Goods, and Convenience Exceptions
Three exceptions cover common nonprofit fundraising activities. If substantially all the work in a trade or business is performed by volunteers without compensation, the income is excluded — the classic example is a volunteer-run bake sale or car wash. Selling merchandise that was donated to the organization is excluded, which is why thrift-store income for many charities is not taxable. And a trade or business carried on primarily for the convenience of members, students, patients, or employees — a school or hospital cafeteria, for instance — is excluded for 501(c)(3) organizations and public colleges.
Where Nonprofits Get Tripped Up
The most common mistakes are not exotic: renting facility space to outside groups on a regular schedule, selling advertising rather than simple sponsorship acknowledgment, running a gift shop that sells general merchandise rather than mission-related items, or treating a genuinely commercial revenue stream as "program income" without applying the three-part test. Debt-financed property can also generate unrelated business income even from otherwise passive activities, which surprises organizations that assumed real estate income was automatically safe.
Why UBIT Rarely Threatens Exempt Status — But Still Matters
A reasonable amount of unrelated business income does not usually jeopardize a nonprofit’s tax-exempt status; the IRS taxes the activity, it does not revoke the exemption, unless unrelated activity becomes so large that it calls into question whether the organization is still primarily operated for its exempt purpose. But ignoring a filing requirement is its own problem: a missed Form 990-T means penalties and interest accruing on tax that was always due, discovered later at the worst possible time — often during an audit or a grant application that asks for clean compliance history.
How VarStan Helps
Most nonprofits do not set out to run a taxable side business — the UBIT exposure usually shows up gradually, as a fundraising program grows or a building gets rented out to cover costs. As a CPA-led firm, we review nonprofit revenue streams against the UBIT exceptions, flag activities that need a closer look, and prepare Form 990-T when it is required, so a good fundraising idea does not turn into an unexpected tax bill. If your organization has any revenue beyond donations and grants, it is worth having someone check it against the UBIT rules.
Related reading: Nonprofit Fraud: Protecting Your Organization From Internal Theft and Cash Reserves for Nonprofits: Building a Financial Cushion.