What it means
The alternative structure is a revenue bond, which is repaid only from the cash a specific asset generates, such as a toll road or an airport terminal. A general obligation bond, often shortened to GO bond, has no such ring fence; it is a claim on the issuer's general finances.
That broader backing is why these bonds usually carry lower interest rates than revenue bonds from the same issuer. Investors are lending against a tax base rather than against the commercial success of one project, and tax bases are far more predictable than passenger numbers or toll receipts.
Governments use general obligation bonds for things that do not produce revenue: schools, parks, courthouses, flood defences and general road maintenance. Because taxpayers ultimately stand behind the debt, many jurisdictions require a public vote before an issue can proceed.
There are two common variants. An unlimited tax general obligation bond allows the issuer to raise property tax rates as far as needed to service the debt, while a limited tax version caps the rate, which makes the security weaker and the yield a little higher.
For investors in the United States, interest on these bonds is often exempt from federal income tax, which changes how the yield should be compared with corporate debt. The right comparison uses the taxable-equivalent yield rather than the stated coupon.
In practice
Real-world examples
Example 1
A school district asks voters to approve $50,000,000 of general obligation bonds to rebuild two ageing schools. The ballot material states the expected property tax cost as $0.90 per $1,000 of assessed value in the first year.
Example 2
A retired investor in a high tax bracket compares a 4% general obligation bond with a 5.5% corporate bond. After adjusting for the tax exemption, the tax-equivalent yield of 5.88% makes the municipal bond the better after-tax choice.
Example 3
A city that has run three consecutive deficits is downgraded by a rating agency, and its next general obligation issue prices at 4.6% instead of the 4.0% it paid two years earlier. On a $50,000,000 issue that adds $300,000 a year in interest at the outset.
Think of it
Imagine a homeowner borrowing money to renovate their kitchen, promising to use their steady monthly salary from their day job to pay it back, regardless of whether the kitchen helps them make money.
Formula
Calculation
Annual debt service = principal repaid in the year + (outstanding principal x coupon rate). Required tax levy rate = annual debt service / total assessed value of the tax base.
A school district issues $50,000,000 of general obligation bonds with a 4% coupon, repaying principal in twenty equal instalments of $50,000,000 / 20 = $2,500,000 a year. In the first year, interest is $50,000,000 x 4% = $2,000,000, so debt service is $2,500,000 + $2,000,000 = $4,500,000.
The district's assessed property tax base is $5,000,000,000. The levy needed in year one is $4,500,000 / $5,000,000,000 = 0.09%, which is $0.90 per $1,000 of assessed value. A home assessed at $300,000 therefore pays 300 x $0.90 = $270 a year towards the bonds.
The burden falls each year. In year two the outstanding balance is $47,500,000, interest is $1,900,000, and debt service is $2,500,000 + $1,900,000 = $4,400,000. For an investor paying tax at a 32% marginal rate, a 4% tax-exempt coupon is worth 4% / (1 - 0.32) = 5.88% before tax, which is the number to compare against a taxable corporate bond.Case study
Seen in the real world
The City of Larkspur Falls is a fictional municipality used for this illustrative case. Its council needed $50,000,000 to replace a failing water treatment plant and a set of collapsing bridges, and the finance team debated whether to use revenue bonds backed by water charges or general obligation bonds backed by the tax base.
The water plant could plausibly support a revenue bond, since it produced billable income, but the bridges could not. The team modelled a single $50,000,000 general obligation issue at 4% over twenty years, giving first-year debt service of $4,500,000 and a levy of $0.90 per $1,000 against an assessed base of $5,000,000,000, or $270 a year on a $300,000 home.
In the illustrative ballot campaign, presenting the cost as $270 a year on a typical home proved far more persuasive than the $50,000,000 headline. The measure passed, the bonds priced at 4%, and the council committed to publishing the declining debt service schedule each year so residents could see the levy fall as the principal was repaid.
Watch out
Common mistakes
- Assuming all municipal bonds carry the same security, when general obligation and revenue bonds rest on completely different sources of repayment.
- Comparing a tax-exempt coupon directly with a taxable corporate yield instead of converting it to a taxable-equivalent figure.
- Treating a general obligation pledge as risk-free, since issuers can and occasionally do default, and limited tax versions constrain the very remedy investors rely on.
Questions
People also ask
What backs a general obligation bond?
The issuer's full faith, credit and taxing power, rather than the cash flows of any single project.
Why do these bonds usually yield less than revenue bonds?
Because the repayment source is a whole tax base rather than one asset's income, which makes default materially less likely.
Do voters always have to approve them?
Not always, but many jurisdictions require voter approval for unlimited tax general obligation debt because it commits future taxpayers.