Credit Ratings: General Obligation vs Revenue Municipal Bonds

General obligation bonds and revenue bonds are rated by the same agencies on fundamentally different criteria—because they’re backed by different sources of repayment. A credit rating reflects the issuer’s ability to repay debt, but GO bonds are secured by the taxing power of the municipality, while revenue bonds depend on the cash flow from a specific project or utility. This structural difference is why GO bonds typically receive higher ratings for the same issuer.

Why the same issuer gets different ratings

A city with an AA credit-rating for its general obligation bonds might issue a BBB-rated revenue bond for its municipal airport—even though both are issued by the same municipality. This gap reflects a hard truth: the two instruments rely on entirely different revenue sources, and so they carry different risks.

A general obligation bond is backed by the full faith and credit of the issuing municipality. If the city faces revenue shortfalls, it is legally obligated to raise property taxes, cut spending, or both to meet debt obligations. This broad-based repayment pledge gives GO bonds a senior claim on the city’s resources and makes defaults rare. Revenue bonds, by contrast, are backed only by the cash generated from a specific project—an airport, toll road, parking garage, or water system. If that project generates less revenue than expected, bondholders have no claim on the city’s tax revenue.

Consequently, credit rating agencies apply different analytical frameworks to each type. For GO bonds, raters focus on the municipality’s overall financial health: population trends, diversity of the tax base, existing debt burden, fund reserves, and the willingness of voters and elected officials to manage finances prudently. For revenue bonds, raters focus on the specific project: projected ridership or usage, competition, management competence, renewal needs, and whether revenues are sufficient to cover both operating costs and debt service.

The GO bond advantage: full-faith backing

General obligation bonds sit at the top of a municipality’s payment hierarchy. If a city must choose between paying its general obligation bonds and its revenue bonds, GO bondholders are paid first. This seniority matters because it creates insurance against financial stress.

Consider a city facing a recession. Tax revenues fall. Rather than default on GO bonds—which would trigger fiscal crisis and potentially bankruptcy—the city will cut spending elsewhere, defer capital projects, or raise tax rates. These painful choices are possible and frequently made. But walking away from a legal obligation to repay GO bonds backed by the taxing power carries political and legal catastrophe. As a result, GO bond defaults are historically uncommon; defaults tend to occur when a city is already in true insolvency.

Revenue bonds have no such fallback. If the municipal parking system generates $2 million in revenue annually but the bond covenant requires $3 million in debt service, there is no city budget surplus to cover the gap. The project must either improve operations, refinance at lower rates, or default. This constraint is why revenue bonds for unproven or cyclical projects (like convention centers or entertainment venues) are rated lower—sometimes much lower—than the issuer’s GO bonds.

How raters assess GO bonds

When assigning a credit rating to general obligation municipal bonds, agencies examine four broad categories.

Tax base and economic health. Raters study population, median income, employment diversity, and major employers. A city dependent on a single large employer or industry faces higher risk if that employer relocates or contracts. A diversified, growing population supports stable tax revenues. Growing property values and rising per-capita income typically improve ratings.

Debt burden. Raters compare total outstanding GO debt to assessed property value, and to personal income of residents. High debt levels relative to the tax base signal weaker capacity to absorb a downturn or emergency.

Fund balance and reserves. Cities that maintain cash reserves equivalent to 6 months or more of operating expenditures are rated more favorably than those running paycheck-to-paycheck. Strong reserves allow cities to weather revenue disruptions without cutting services or defaulting on bonds.

Expenditure control and fund-accounting practices. Do city councils approve budgets that spend more than projected revenues? Are accounting controls tight, and financial reporting transparent? Disciplined fiscal management signals lower risk.

How raters assess revenue bonds

Revenue bond ratings focus narrowly on the project’s ability to generate sufficient revenue to cover operating costs and debt service.

Demand projections. For an airport bond, raters examine passenger forecasts, the airport’s competitive position, and airline commitments. For a toll road, they model traffic volumes and pricing. Overoptimistic demand forecasts are a leading cause of revenue bond stress.

Operating margins. Raters calculate the ratio of revenues to operating expenses. If a water utility has tight margins and faces capital-intensive renewal cycles, each downturn in demand poses default risk. Wider margins create a cushion.

Coverage ratios. A typical covenant requires that annual revenues cover debt service by a minimum ratio—often 1.25x or higher. Raters verify that this coverage is achievable under realistic downside scenarios, not just base-case projections.

Renewal and competition. What happens when major infrastructure ages and requires replacement? For a parking garage, can parking fees rise without losing customers to new competitors, or must the operator cut corners? Raters assess both the financial and operational flexibility available to management.

Why GO bonds typically rate higher

The typical spread between a city’s GO rating and its revenue bond ratings is 1 to 3 notches on the rating scale. A city with an AA-rated GO bond might issue A or BBB-rated revenue bonds. This hierarchy reflects financial reality: the GO bond has recourse to all city revenues and taxing power; the revenue bond does not.

However, there are exceptions. A revenue-backed utility bond for a mature water or electric system—one with stable, inflation-resistant demand—may actually be rated higher than a GO bond from a fiscally troubled city. But in most cases, especially for projects with cyclical demand or execution risk, revenue bonds carry more default risk than GO bonds from the same issuer.

The practical implication for yield spreads

This rating difference translates directly into borrowing costs. A city that can issue 20-year GO bonds at 3.5% may have to pay 4.5% to 5.0% to issue revenue bonds for a parking or convention center project. Investors demand the extra yield to compensate for the higher credit risk and narrower source of repayment. This gap widens when the project is new, demand is uncertain, or the local economy is softening.

Municipal bond buyers should understand that a higher coupon rate on a revenue bond does not necessarily mean better value. The higher yield reflects genuine, higher credit risk. A careful investor reads the revenue bond prospectus, models revenues under multiple scenarios, and then decides whether the additional yield justifies that risk.

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