A housing bond is a debt security that a state or local government agency sells to investors, using the proceeds to make housing more affordable for people who meet income limits. The money funds one of two things: below-market mortgages for first-time homebuyers, or loans to developers building or renovating rental properties with units reserved for lower-income tenants. Because federal law exempts the interest investors earn from federal income tax, the issuer can borrow at a lower rate, and that discount flows through to the homebuyer or the rental project.
How the Bond Actually Works
The mechanics are straightforward. A government agency issues bonds. Investors buy them, collect periodic interest, and get their principal back at maturity. The cash raised is loaned out for a housing purpose, and the loan payments coming back in are what pay bondholders.
Almost all housing bonds are revenue bonds, not general obligation bonds. That distinction shapes the risk. A general obligation bond is backed by the government’s power to tax, so if a project underperforms, taxpayers absorb the loss. A revenue bond is repaid only from the income the financed project generates, whether that’s mortgage payments from homebuyers or rent collected from tenants. If those cash flows fall short, bondholders take the hit. That is why project underwriting and credit quality carry so much weight in this corner of the municipal market.
Housing bonds split into two categories, each with its own federal rulebook: single-family mortgage revenue bonds and multifamily housing bonds.
Single-Family Mortgage Revenue Bonds
Single-family mortgage revenue bonds (MRBs) fund below-market home loans. The proceeds go to participating mortgage lenders, who then originate mortgages at interest rates lower than the private market would offer. The savings come directly from the tax exemption: investors accept a lower yield because the interest is tax-free, borrowing costs drop, and the discount reaches the buyer.
Section 143 of the Internal Revenue Code sets tight rules on who can use these mortgages and what homes they can buy.
Who Qualifies
The borrower generally must be a first-time homebuyer, meaning someone with no ownership interest in a principal residence during the three years before closing.1Office of the Law Revision Counsel. 26 USC 143 – Mortgage Revenue Bonds: Qualified Mortgage Bond and Qualified Veterans Mortgage Bond Veterans’ mortgage bonds are a separate category and don’t carry this three-year rule.
Family income cannot exceed 115% of area median family income. For households of fewer than three people, the cap drops to 100%.1Office of the Law Revision Counsel. 26 USC 143 – Mortgage Revenue Bonds: Qualified Mortgage Bond and Qualified Veterans Mortgage Bond In designated targeted areas the ceilings rise to 140% and 120%, and up to a third of bond financing in those areas can go out without any income test.
What Homes Qualify
The home’s purchase price cannot exceed 90% of the average area purchase price for comparable properties, computed separately for new and previously occupied homes so the cap tracks the local market. In targeted areas the ceiling is 110%.2Office of the Law Revision Counsel. 26 US Code 143 – Mortgage Revenue Bonds: Qualified Mortgage Bond and Qualified Veterans Mortgage Bond The point of the price caps is to steer the subsidy toward modest homes. A buyer who fits the income test but wants a house above the ceiling has to use conventional financing.
Multifamily Housing Bonds
Multifamily housing bonds finance the construction, acquisition, or rehabilitation of rental properties that include income-restricted units. The proceeds go to the developer as a low-interest loan, and the developer signs a regulatory agreement locking in affordability for a long period, often 30 years or more.3eCFR. 24 CFR 266.505 – Regulatory Agreement Requirements
Section 142(d) of the Internal Revenue Code requires a multifamily project to meet one of two set-aside tests, chosen at the time the bond is issued:4Office of the Law Revision Counsel. 26 USC 142 – Exempt Facility Bond
- 20/50 test: at least 20% of units occupied by tenants at or below 50% of area median gross income.
- 40/60 test: at least 40% of units occupied by tenants at or below 60% of area median gross income.
The set-aside has to be maintained at all times during the qualified project period, not just at initial lease-up. The choice between the two tests is permanent for a given bond issue. Most developers pick the 40/60 test because the higher income ceiling widens the tenant pool and makes units easier to fill.
Why the Interest Is Tax-Exempt
The financial engine is Section 103 of the Internal Revenue Code, which excludes interest on state and local bonds from gross income.5Office of the Law Revision Counsel. 26 US Code 103 – Interest on State and Local Bonds Investors accept a lower rate on tax-free interest because they keep more of what they earn, and the issuer’s lower borrowing cost turns into cheaper loans for homebuyers and developers.
Technically, housing bonds are Private Activity Bonds (PABs), because more than 10% of proceeds benefit private parties like lenders or developers.6Office of the Law Revision Counsel. 26 US Code 141 – Private Activity Bond; Qualified Bond PABs usually lose the tax exemption, but Congress carved out exceptions for specific public-purpose uses, including residential rental projects under Section 142 and qualified mortgage bonds under Section 143.4Office of the Law Revision Counsel. 26 USC 142 – Exempt Facility Bond Housing bonds that meet these requirements keep the exemption.
One catch for investors: interest from PABs, including housing bonds, is generally included when calculating the Alternative Minimum Tax. Higher-income investors caught by the AMT may not capture the full benefit of the exemption. When the bondholder lives in the state that issued the bond, the interest may also be exempt from state and local income tax, producing a triple tax-free return for investors not subject to AMT.
Why Supply Is Limited: The Volume Cap
The tax exemption costs the federal government revenue, so Congress caps how many PABs each state can issue in a year. Section 146 sets the annual volume cap as the greater of a per-capita amount times state population or a minimum dollar floor.7Office of the Law Revision Counsel. 26 US Code 146 – Volume Cap For 2026, the per-capita figure is $135 and the floor is $397,625,000. Anything issued above a state’s cap loses tax-exempt status.
The cap covers all PABs, not just housing. Infrastructure, airport projects, and student loan programs draw from the same pool. State governments decide how to divide it, and in high-demand states the competition for cap allocation is intense. A project that misses out one year may have to wait.
Who Issues Housing Bonds
State and local Housing Finance Agencies (HFAs) are the public bodies that issue and manage housing bonds. They sit between the investors buying the bonds and the developers or lenders using the proceeds. The HFA structures the transaction, underwrites each proposed project, and monitors compliance with federal tax and housing rules for the life of the bond.
For single-family MRBs, the HFA deposits proceeds with participating lenders through an allocation agreement, and those lenders originate mortgages for eligible borrowers at the subsidized rate. For multifamily bonds, the HFA lends the proceeds directly to the developer to cover construction or rehabilitation costs.
How Multifamily Bonds Pair With Tax Credits
Multifamily housing bonds rarely stand alone. Developers usually combine the cheap debt from bond financing with equity raised by selling Low-Income Housing Tax Credits (LIHTCs). The bond supplies low-cost capital, and the credits attract equity investors who trade cash upfront for a decade of tax benefits. That pairing is what makes affordable rental deals pencil out.
Under Section 42(h)(4), a building financed with tax-exempt bonds can receive the 4% LIHTC without competing for a separate state allocation, provided the bond financing meets a minimum threshold. For decades that threshold was 50% of the building’s aggregate basis, including land. Legislation signed in July 2025 lowered the threshold to 25% for bonds issued after December 31, 2025.8Office of the Law Revision Counsel. 26 USC 42 – Low-Income Housing Credit
The drop matters. Under the old rule, a developer had to finance at least half the project with tax-exempt bonds to unlock credits on all the low-income units, and falling below 50% meant only proportional credits. The 25% threshold consumes less volume cap per project, freeing capacity for more deals across a state. For acquisition-rehabilitation projects, the relevant placed-in-service date is when the rehabilitation is placed in service, not when the building was originally acquired.
What Homebuyers Should Know About Recapture
Anyone using a mortgage financed by a single-family housing bond should understand the federal mortgage subsidy recapture tax. If you sell or otherwise dispose of the home within nine years of receiving the subsidized loan, and your income has grown past a threshold set by the issuer, the IRS may recapture part of the subsidy.9Internal Revenue Service. Instructions for Form 8828, Recapture of Federal Mortgage Subsidy
The maximum recapture is 6.25% of the highest outstanding balance of the subsidized loan. That number is multiplied by a holding-period percentage that starts at 20% in the first year and shifts over time, and it’s reduced further if your income at sale stays below the adjusted qualifying income threshold your bond issuer gave you at closing.9Internal Revenue Service. Instructions for Form 8828, Recapture of Federal Mortgage Subsidy
In practice, recapture only bites when two things happen together: you sell relatively early, and your income has climbed substantially. Stay in the home nine full years and you owe nothing regardless of income. Sell in year three with modest income growth and you likely owe nothing either. The tax is reported on IRS Form 8828 and added to income tax for the year of the sale. Refinancing within the first four years recalculates the holding-period percentage as if you had repaid the loan, which can raise your exposure.