Sting Tax: UBIT Rules, Rates, and Filing Requirements

The sting tax is the informal name tax professionals use for the Unrelated Business Income Tax, or UBIT, a federal tax that tax-exempt organizations and certain retirement accounts owe on income from commercial activities unrelated to their exempt purpose. The rate is a flat 21% for most exempt organizations and reaches 37% for trusts, which includes IRAs. The nickname captures what makes the rule bite: people assume tax-exempt status shields everything the organization or account earns, when it actually shields only income tied to the exempt mission or held as truly passive investment.

Who Pays It and Why It Exists

Congress built UBIT to stop exempt organizations from using their tax advantage to undercut for-profit competitors. A charity running a commercial business tax-free has an enormous edge over the taxable business next door, and Sections 511 through 514 of the Internal Revenue Code close that gap by taxing the commercial profits while leaving mission-related revenue alone.¹

Nearly every exempt entity can owe it: 501(c)(3) charities, 501(c)(4) social welfare groups, 501(c)(6) trade associations, state college and university instrumentalities, and most other organizations exempt under Section 501(a). The narrow exception is organizations exempt under Section 501(c)(1).¹ IRAs and several other trust-based savings vehicles are also exposed, which is covered in detail below.

When Income Counts as Unrelated

Income triggers the sting tax only when the activity fails all three parts of a statutory test. The activity 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.² Miss any one element and the income escapes.

“Trade or business” is broad. Any activity producing income from selling goods or performing services counts, even if it runs at a loss. “Regularly carried on” 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. A state fair association running a two-week annual event probably falls short, but if that same association leases its grounds to commercial vendors the rest of the year, the leasing stands on its own and likely qualifies.

The last element trips the most people up. “Not substantially related” asks whether the activity itself advances the mission, not whether the money does.³ 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 and art reproductions is related; selling consumer electronics is not. Directing the profits to the exempt mission does not save the activity.

What’s Carved Out

Even when an activity meets all three parts of the test, three categories are never treated as unrelated business:

Businesses in which substantially all the work is performed by unpaid volunteers (a classic example being a volunteer-staffed thrift store).³
Activities run primarily for the convenience of a 501(c)(3) or government college’s own members, students, or patients, such as a school cafeteria.⁴
Sales of merchandise that was received as a gift or contribution, which is why charity shops selling donated clothing generally owe no UBIT no matter how many paid staff they employ.³

Most passive investment income is also outside the UBIT calculation. The code excludes dividends, interest, annuities, royalties, and rent from real property.² Research income earned by a college, university, or hospital is fully excluded. Exchanging or renting donor and member mailing lists between organizations eligible to receive tax-deductible contributions is excluded as well; renting those lists to for-profit companies is not.⁵

Rent gets technical when real and personal property are leased together. If the personal-property portion is 10% of the total rent or less, all the rent stays excluded. Between 10% and 50%, only the real-property share is excluded. Above 50%, the entire rent becomes taxable.⁶ Rent that varies with a tenant’s net income or profits also loses the safe harbor, though rent set as a fixed percentage of gross receipts remains excluded.²

Where Passive Stops Being Passive

Two situations pull otherwise passive income back into the tax. The first is debt-financed property under Section 514: when an exempt organization or IRA uses borrowed money to acquire or improve an income-producing asset, the share of income tied to that debt loses the passive exclusion.⁷ The calculation is proportional. If average acquisition debt equals 60% of the property’s average adjusted basis for the year, 60% of the rental income and 60% of the allocable deductions enter the UBTI calculation. As the loan is paid down, the taxable share shrinks, and once the property is debt-free the full exclusion returns.

The second is payments from a controlled entity. If an exempt organization receives interest, rent, royalties, or annuities from a subsidiary it controls (more than 50% by vote, value, or beneficial interest), those payments are pulled into UBTI to the extent they exceed an arm’s-length price and reduce the subsidiary’s own taxable or unrelated income.² The rule stops organizations from stripping income out of a controlled sub through inflated rent or royalty payments.

Sponsorships Versus Advertising

Corporate sponsorship is where many nonprofits accidentally generate UBIT. A qualified sponsorship payment is money, property, or services from a business that expects nothing substantial in return beyond acknowledgment of its name, logo, or product lines.³ Acknowledgment means neutral recognition: displaying a logo, listing contact details, linking to the sponsor’s homepage.

Cross into comparative language, pricing information, savings claims, endorsements, or calls to action and the payment becomes advertising income subject to UBIT. An exclusive-provider arrangement that blocks the sponsor’s competitors also triggers the tax. Where 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.

How the Sting Tax Hits IRAs

This is where the “sting tax” nickname earns itself. An IRA is a tax-exempt trust, and like any other exempt trust it can owe UBIT. Most retirement investors never find out until a tax form arrives.

The usual trigger is a master limited partnership or other operating partnership held inside the account that reports business income on a Schedule K-1. If the account’s share of that income, combined across all applicable investments, reaches $1,000 or more, the IRA must file Form 990-T and pay the tax.⁸ The tax comes directly out of the IRA’s cash balance, and the custodian pays it to the IRS 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.

Each retirement account is a separate trust, even if one person owns several IRAs. Every account has its own $1,000 threshold and needs its own employer identification number if it must file.⁸ The filing requirement reaches beyond traditional IRAs to Roth IRAs, SEP IRAs, SIMPLE IRAs, Coverdell education savings accounts, Archer MSAs, and health savings accounts.

Debt inside an IRA causes the same problem. If the account borrows to acquire property, which happens often with leveraged real estate, the income attributable to the financed share loses the passive-income exclusion and becomes UBTI under the Section 514 proportional calculation.

Rates and the $1,000 Deduction

Most exempt organizations pay the sting tax at the flat 21% corporate rate. Exempt trusts, including IRAs, pay at the compressed trust income tax rates instead. For 2025, the top trust rate of 37% kicked in above roughly $15,200. For 2026, if Congress does not extend the current structure, the top trust rate reverts to 39.6%.⁹

Every filer gets a flat $1,000 specific deduction against net UBTI.² The deduction is excluded from the net operating loss calculation, so it cannot create or increase a loss carryforward.

Filing and Paying

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.¹⁰ The deadline depends on the entity. Organizations taxed at corporate rates file by the 15th day of the fifth month after year-end, so May 15 for a calendar-year filer.¹¹ Trusts file by the 15th day of the fourth month, so April 15 for a calendar-year trust.

For tax years ending in December 2020 and later, Form 990-T must be filed electronically. Paper filing is no longer accepted.¹²

Any organization that expects to owe $500 or more in UBIT for the year must make quarterly estimated payments. The IRS provides Form 990-W as a worksheet, with installments generally running 25% of the expected annual liability per quarter.¹³ Any remaining balance is due by the return’s due date, and an extension of time to file does not extend the time to pay.

When Unrelated Business Threatens the Exemption Itself

The sting tax is meant to tax commercial profits, not strip an organization of its exempt status. But at some point the volume of unrelated activity calls the exemption itself into question. The IRS publishes no bright-line percentage, and no statutory threshold triggers automatic revocation. In practice, many tax advisors treat unrelated revenue above roughly 15% to 20% of total income as a warning sign that invites heightened scrutiny.

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

1
Office of the Law Revision Counsel. 26 U.S. Code 511 – Imposition of Tax on Unrelated Business Income of Charitable, Etc., Organizations
2
Office of the Law Revision Counsel. 26 U.S. Code 512 – Unrelated Business Taxable Income
3
Office of the Law Revision Counsel. 26 U.S. Code 513 – Unrelated Trade or Business
4
Internal Revenue Service. Unrelated Business Income Tax Exceptions and Exclusions
5
Internal Revenue Service. Identification and Treatment of Income from Mailing Lists
6
Internal Revenue Service. Rents from Personal Property, Mixed Leases, and the Rental Exclusion from UBTI
7
Office of the Law Revision Counsel. 26 U.S. Code 514 – Unrelated Debt-Financed Income
8
Internal Revenue Service. Instructions for Form 990-T
9
Internal Revenue Service. Unrelated Business Income Tax Returns
10
Internal Revenue Service. Unrelated Business Income Tax
11
Internal Revenue Service. Return Due Dates for Exempt Organizations – Form 990-T (Corporations)
12
Internal Revenue Service. E-File for Charities and Nonprofits
13
Internal Revenue Service. Estimated Tax: Unrelated Business Income