Private Activity Bond

A private activity bond is defined by IRC 141(a): "the term "private activity bond" means any bond issued as part of an issue— (1) which meets— (A) the private business use test of paragraph (1) of subsection (b), and (B) the private security or payment test of paragraph (2) of subsection (b), or (2) which meets the private loan financing test of subsection (c)." It is a category of municipal bond, issued by a state or local government, and what sets it apart is who actually uses the money and who actually pays it back. When the answer to both is a private business rather than the public, the bond is a private activity bond, and the federal tax exemption that municipal bonds ordinarily enjoy is no longer automatic.

The section's title, "Private activity bond; qualified bond," names the two halves of the subject. The first half is the definition, a set of percentage tests. The second is the list of private activity bonds Congress has decided should keep their exemption anyway, because the private use serves a public purpose the tax law wants to subsidize: airports, low-income housing, student loans, small manufacturers, nonprofit hospitals and universities. The municipal bond page states the tax consequences in the course of explaining the exclusion's four holes; this page is about the definition, the tests, the qualified categories and the cap that limits them.

The two-part private business test. IRC 141(b)(1) is the private business use test: an issue meets it "if more than 10 percent of the proceeds of the issue are to be used for any private business use." IRC 141(b)(2) is the private security or payment test: an issue meets it "if the payment of the principal of, or the interest on, more than 10 percent of the proceeds of such issue is (under the terms of such issue or any underlying arrangement) directly or indirectly" secured by property used in a private business or by payments in respect of it, or derived from such payments. Both must be met. A bond that funds a facility leased to a company but is repaid entirely from general taxes fails the second test; a bond repaid from a company's payments for a facility the public uses fails the first. Under 141(b)(3) the threshold drops to 5 percent where the private use is "not related" to the governmental use being financed, or is disproportionate to it.

What "private business use" means, and what it does not. IRC 141(b)(6)(A) defines it as "use (directly or indirectly) in a trade or business carried on by any person other than a governmental unit," and then adds the sentence that keeps ordinary public facilities out of the definition: "For purposes of the preceding sentence, use as a member of the general public shall not be taken into account." A toll road used by trucking companies is not a private business use because the trucks use it as members of the public; the same road leased to one company to operate would be.

The loan test. IRC 141(c)(1) catches bonds that lend the money onward: an issue meets the private loan financing test if the proceeds used "to make or finance loans ... to persons other than governmental units exceeds the lesser of— (A) 5 percent of such proceeds, or (B) $5,000,000." This test stands alone; a bond that meets it is a private activity bond whether or not the business tests are met. The $5,000,000 is written into the statute and is not indexed.

Qualified bonds keep the exemption. IRC 141(e)(1) lists the categories: a private activity bond is a qualified bond if it is "(A) an exempt facility bond, (B) a qualified mortgage bond, (C) a qualified veterans' mortgage bond, (D) a qualified small issue bond, (E) a qualified student loan bond, (F) a qualified redevelopment bond, or (G) a qualified 501(c)(3) bond," and, under 141(e)(2) and (3), meets the volume cap requirements of section 146 and the other requirements of section 147. Exempt facility bonds finance a list of facilities set out in section 142, such as airports, docks and qualified residential rental projects; qualified mortgage bonds finance home loans, the mortgage revenue bonds behind many first-time homebuyer programs; qualified 501(c)(3) bonds finance nonprofit hospitals and universities, and the MSRB names them among the common types of conduit financing. The municipal bond page defines the conduit structure. Publication 550 restates the same list for taxpayers and adds the consequence: "Interest on a private activity bond that is a qualified bond is tax exempt."

The volume cap rations the exemption. IRC 146(a) provides that a private activity bond meets the section's requirements only if the issue, added to the tax-exempt private activity bonds the issuing authority has already issued that year, "does not exceed such authority's volume cap for such calendar year." The mechanism is a state ceiling divided in two: under 146(b) the state's own agencies receive 50 percent of it, and under 146(c) every other issuer in the state receives a share of the remaining 50 percent in proportion to its population, though 146(e) lets a state "by law provide a different formula" for dividing its ceiling. The ceiling itself, under 146(d), is the greater of a per-capita amount multiplied by the state's population or a fixed floor, both indexed for inflation each year, and the current figures are published annually by the IRS. This page does not print them. The MSRB's glossary describes the cap as "The aggregate annual amount of private activity bonds (other than qualified veterans' mortgage bonds, qualified 501(c)(3) bonds and certain categories of exempt facility bonds) that may be issued within a state in any calendar year on a tax-exempt basis," which also records the categories the cap does not reach. Unused cap can be carried forward for up to three years under 146(f) for designated purposes.

The two tax consequences, stated once. A private activity bond that is not a qualified bond loses the exemption entirely: IRC 103(b)(1) removes from the exclusion "Any private activity bond which is not a qualified bond (within the meaning of section 141)." A qualified bond keeps the exclusion for regular tax but, under IRC 57(a)(5), its interest is generally an item of tax preference for the alternative minimum tax, with carve-outs for qualified 501(c)(3) bonds and for certain housing bonds. The MSRB's market label for such a bond is an AMT bond, "A tax-exempt bond whose interest is subject to the alternative minimum tax." The alternative minimum tax page covers the preference and its exceptions, and the municipal bond page places both consequences among the exclusion's four holes. Brokers report the preference slice in box 9 of Form 1099-INT, and a municipal bond fund reports it in box 13 of Form 1099-DIV. On the liveness of these rules: the 2025 tax legislation amended section 57 only at paragraph (a)(7), the small business stock provision, and left (a)(5) and section 141 untouched.

Before issuing, the government's bond counsel tests the proposed issue against IRC 141: how much of the proceeds will a private business use, how much of the debt service will private payments secure, and how much will be lent onward. If the issue crosses the thresholds it is a private activity bond, and counsel then asks whether it fits a qualified category, whether the issuer has volume cap available to allocate to it, and whether it meets section 147's other conditions. Only if all three answers are yes does the interest stay exempt for regular tax, and the offering documents then disclose whether it is an AMT bond.

A hypothetical example. A city plans a $50,000,000 bond issue for a new civic center. The plan leases a wing of the building to a private conference operator, and the operator's lease payments will secure part of the debt service.

Version one. The leased wing accounts for $6,000,000 of the proceeds, which is $6,000,000 ÷ $50,000,000 = 12 percent, and the operator's payments secure the same 12 percent of the debt service. Both figures exceed 10 percent, so the issue meets the private business use test and the private security or payment test, and the bonds are private activity bonds. A civic center wing leased to a for-profit conference company is not on the qualified list, so under IRC 103(b)(1) the interest on the issue would be taxable, and the city would have to restructure or accept a taxable borrowing rate.

Version two. The city shrinks the leased wing to $4,000,000 of the proceeds, or 8 percent, with the operator's payments securing 8 percent of the debt service. Neither test is met, the bonds are ordinary governmental bonds, and the interest is exempt under IRC 103(a). Four million dollars of design change decides the tax character of the whole $50,000,000 issue.

The loan test, separately. Suppose instead the city proposes to lend $3,000,000 of the proceeds to local businesses for storefront improvements. The threshold is the lesser of 5 percent of $50,000,000, which is $2,500,000, and $5,000,000, so it is $2,500,000. The $3,000,000 of loans exceeds it, and the issue is a private activity bond under IRC 141(c) regardless of how the rest of the proceeds are used. Capping the loan program at $2,500,000 would keep the issue outside the test.

Pros

• The qualified categories let tax-exempt financing reach airports, affordable housing, student loans, small manufacturers and nonprofit institutions that a purely governmental definition would exclude.
• The tests are numerical and disclosed, so bond counsel can determine a bond's status before issuance and the official statement states it.
• A qualified private activity bond pays exempt interest for regular tax, and for a holder not subject to the alternative minimum tax the preference has no effect, so any extra yield the market attaches to an AMT bond is a benefit without a cost to that holder.

Cons

• Interest on a qualified private activity bond is generally a preference item for the alternative minimum tax, so a bond sold as tax-exempt can produce taxable income for a particular holder.
• A private activity bond that is not a qualified bond is fully taxable, and the word "municipal" on it is no evidence of exemption.
• The credit behind a conduit private activity bond is the private borrower's, not the government issuer's.
• The volume cap rations supply, so qualified bonds for some purposes are scarce and the allocation process is political.
• The tests turn on percentages of proceeds and payments that a bondholder cannot verify, so the holder relies on bond counsel's opinion and the issuer's continuing compliance.