Sting Tax: UBIT Rates, the Silo Rule, and IRA Exposure

The sting tax is the informal name financial and nonprofit professionals use for the Unrelated Business Income Tax, or UBIT: a federal tax that hits tax-exempt organizations and certain retirement accounts on income from commercial activities that fall outside their exempt purpose. Most exempt organizations pay it at the flat 21% corporate rate. Exempt trusts, including IRAs, pay at graduated trust rates that reached 37% at the top bracket in 2025. The tax kicks in once gross unrelated business income for the year reaches $1,000, and it is reported on Form 990-T.¹

The nickname sticks because the tax surprises people. Nonprofit boards assume their exemption covers everything they earn. IRA holders assume nothing inside the account is taxable until they take distributions. Both are wrong in specific, predictable situations.

Who Owes It

UBIT applies to nearly every type of exempt organization: 501(c)(3) charities, 501(c)(4) social welfare groups, 501(c)(6) trade associations, state college and university instrumentalities, and most other entities exempt under Section 501(a).² It also applies to trust-based retirement and savings accounts: traditional IRAs, Roth IRAs, SEP IRAs, SIMPLE IRAs, Coverdell education savings accounts, Archer MSAs, and health savings accounts.³

Congress built the tax to stop exempt entities from using their tax advantage to undercut taxable competitors. A charity running a commercial business tax-free would have an enormous edge over the for-profit next door. Sections 511 through 514 of the Internal Revenue Code close that gap by taxing the commercial profits while leaving mission-related revenue alone.²

What Counts as Unrelated Business Income

An activity produces Unrelated Business Taxable Income (UBTI) only if it meets all three parts of a statutory test. It must be a trade or business, it must be regularly carried on, and it must not be substantially related to the organization’s exempt purpose.⁴ Miss any one element and the income escapes UBIT.

Trade or business. Any activity conducted to produce income from selling goods or performing services qualifies, even at a loss. The definition is broad and mirrors what applies to taxable companies.

Regularly carried on. The IRS compares the frequency and continuity of the activity to how a comparable for-profit business operates. A university bookstore open year-round meets this test. A one-weekend charity auction does not.

Not substantially related. The relationship between the activity and the exempt purpose has to be real, not just a convenient source of funding. That the profits go toward the mission is irrelevant; what matters is whether the activity itself advances the mission.⁵ A hospital pharmacy filling prescriptions for its own patients is related. Opening that pharmacy to the general public to compete with retail drugstores is not. A museum gift shop selling exhibition catalogs is related; selling consumer electronics from the same shop is not.

Activities the Code Excludes Outright

Even when an activity meets all three parts of the test, three carve-outs keep it out of UBTI:

Businesses in which substantially all the work is performed by unpaid volunteers, such as a thrift store staffed almost entirely by volunteers.⁵
Activities carried on primarily for the convenience of members, students, or patients of a 501(c)(3) or government college. A school cafeteria is the classic example.⁶
The sale of donated merchandise, which is why charity thrift stores that sell donated goods generally owe no UBIT regardless of how many paid staff they employ.⁵

Passive Income and Its Exceptions

Most passive investment income stays outside UBTI. Dividends, interest, annuities, royalties, and rent from real property are excluded, along with deductions directly connected to earning them.⁴ Research income earned by a college, university, or hospital is also fully excluded, and exempt organizations eligible to receive tax-deductible contributions can exchange or rent donor and member mailing lists to each other without triggering the tax.⁷

The rent exclusion narrows when personal property is bundled into the lease. If the personal-property share of the rent exceeds 10%, part or all of the rent loses the exclusion; once it tops 50%, the entire rent becomes taxable.⁸ Rent that varies based on a tenant’s income or profits also loses the safe harbor.

Debt-Financed Property

The passive-income shield disappears when the income comes from property acquired or improved with borrowed money. Under Section 514, a proportional share of the income becomes UBTI: if a building’s average acquisition debt during the year equals 60% of its average adjusted basis, then 60% of the rental income and 60% of allocable deductions flow into the UBTI calculation.⁹ As the debt is paid down, the taxable share shrinks. Once the property is debt-free, the full passive-income exclusion applies again.

Payments From Controlled Entities

Interest, rent, royalties, or annuities that an exempt organization receives from an entity it controls (more than 50% by vote, value, or beneficial interest) get pulled back into UBTI to the extent those payments reduce the subsidiary’s own taxable or unrelated income.⁴ The rule blocks organizations from setting up a subsidiary, paying themselves inflated rents or royalties, and sheltering the income under the passive-income exclusion.

Sponsorships Versus Advertising

Corporate sponsorship is a major revenue source for many exempt organizations, and the line between a tax-free sponsorship payment and taxable advertising income is thinner than most people assume. A qualified sponsorship payment is money, property, or services from a business that receives no substantial benefit in return beyond acknowledgment of its name, logo, or product lines.⁵

Acknowledgment is neutral: displaying the sponsor’s logo, listing contact details, or linking to the sponsor’s homepage. Comparative language, pricing, savings claims, endorsements, or calls to action turn the payment into advertising income subject to UBIT. Exclusive-provider arrangements that block competitors do the same. When a sponsor does receive some return benefit, only the portion of the payment exceeding the fair market value of that benefit qualifies as a tax-free sponsorship.

The Silo Rule for Multiple Activities

Organizations with more than one unrelated business cannot lump the results together. Section 512(a)(6) requires computing UBTI separately for each unrelated trade or business, and any single activity’s taxable income cannot drop below zero.⁴ A loss from one commercial venture cannot shelter the profits from another. Net operating loss deductions follow the same per-activity framework.¹⁰ The $1,000 specific deduction is applied only once, after the separate results are combined.

How the Sting Tax Hits IRAs

This is where the nickname earns its keep. An IRA is itself a tax-exempt trust, and when it holds investments that generate business income rather than passive returns, the account owes UBIT.

The most common trigger is a master limited partnership or other operating partnership that reports business income to the account on a Schedule K-1. Once the IRA’s total UBTI across all such investments reaches $1,000 for the year, the account must file Form 990-T and pay the tax.³ The tax comes directly out of the IRA’s cash balance, and the custodian pays it on the account’s behalf. It is not treated as a distribution, so there is no additional income tax or early withdrawal penalty on the payment itself.

The IRS treats each retirement account as a separate trust, even if one person owns several IRAs. Each account has its own $1,000 threshold and needs its own employer identification number if it has to file.³

Debt-financed investments inside an IRA create the same problem. If the IRA borrows to acquire property, which happens often with leveraged real estate, the income tied to the financed portion loses its passive-income exclusion and becomes UBTI under the same Section 514 proportional calculation.

Rate, the $1,000 Deduction, and Expense Allocation

Most exempt organizations pay UBIT at the flat 21% corporate rate. Exempt trusts, including IRAs, use graduated trust rates instead, which compress far faster than individual brackets. In 2025, the top trust rate of 37% applied to income above roughly $15,200. If Congress does not extend the current rate structure, the top trust rate reverts to 39.6% in 2026.¹¹

Every filer gets a $1,000 specific deduction against net UBTI.⁴ The deduction is excluded from the net operating loss calculation, so it cannot create or increase a loss carryforward.

When the same space, equipment, or staff serves both exempt and unrelated activities, expenses must be allocated between the two on a reasonable basis. Only the share attributable to the unrelated business is deductible against UBTI. The IRS does not prescribe a single method; it asks that the allocation be reasonable and consistently applied.

Filing and Payment

Any exempt organization or retirement account trust with $1,000 or more in gross income from an unrelated trade or business must file Form 990-T.¹ For organizations taxed at corporate rates, the return is due the 15th day of the fifth month after the tax year ends, which is May 15 for calendar-year filers.¹² For trusts, the deadline is the 15th day of the fourth month, or April 15 for calendar-year filers.

Form 990-T must be filed electronically for tax years ending December 2020 and later. Paper filing is no longer accepted.¹³

Filers expecting $500 or more in UBIT liability for the year must make quarterly estimated payments, generally 25% of the expected annual liability per quarter. Form 990-W works as the calculation worksheet.¹⁴ Any remaining balance is due in full by the return’s due date. An extension of the filing deadline does not extend the payment deadline.

When Commercial Activity Threatens Exempt Status

UBIT taxes commercial profits; it does not, by itself, endanger exempt status. But volume matters. The IRS publishes no bright-line percentage and no statutory threshold triggers automatic revocation. In practice, tax advisors commonly treat unrelated revenue running above roughly 15% to 20% of total income as a warning sign that invites heightened scrutiny.

The real test is qualitative: has the commercial activity become so central to operations that it has displaced the exempt mission? An organization generating more revenue from its gift shop than from its programs, or devoting more staff time to commercial operations than to charitable work, is exposed. Consequences range from audit attention to full revocation, which would make all the organization’s income taxable going forward. Spinning off significant unrelated activities into a separate taxable subsidiary is the most common way to manage that risk while preserving the parent organization’s exemption.

1
Internal Revenue Service. Unrelated Business Income Tax
2
Office of the Law Revision Counsel. 26 U.S. Code 511 – Imposition of Tax on Unrelated Business Income of Charitable, Etc., Organizations
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Internal Revenue Service. Instructions for Form 990-T
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Office of the Law Revision Counsel. 26 U.S. Code 512 – Unrelated Business Taxable Income
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Office of the Law Revision Counsel. 26 U.S. Code 513 – Unrelated Trade or Business
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Internal Revenue Service. Unrelated Business Income Tax Exceptions and Exclusions
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Internal Revenue Service. Identification and Treatment of Income from Mailing Lists
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Internal Revenue Service. Rents from Personal Property, Mixed Leases, and the Rental Exclusion from UBTI
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Office of the Law Revision Counsel. 26 U.S. Code 514 – Unrelated Debt-Financed Income
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eCFR. 26 CFR 1.512(a)-6 – Special Rule for Organizations With More Than One Unrelated Trade or Business
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Internal Revenue Service. Unrelated Business Income Tax Returns
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Internal Revenue Service. Return Due Dates for Exempt Organizations – Form 990-T (Corporations)
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Internal Revenue Service. E-File for Charities and Nonprofits
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Internal Revenue Service. Estimated Tax: Unrelated Business Income