Municipal bonds are generally considered safer than stocks, but they carry real risks that depend on who issued the bond and what happens to that issuer's finances

A municipal bond is a loan you make to a city, county, school district, or other local government. They pay you back with interest over a set period. The safety of that repayment depends almost entirely on whether the issuer can collect enough tax revenue or other income to pay you back on time. Unlike stocks, where your money can vanish overnight, municipal bonds have a legal obligation behind them — but that obligation is only as strong as the issuer's ability to pay.

The biggest factor in safety is the issuer's credit rating. Agencies like Moody's, Standard & Poor's, and Fitch grade municipal bonds the same way they grade corporate bonds. A bond rated AAA or AA is considered very safe. A bond rated BBB or lower carries real risk that the issuer might not pay you back in full or on time. Before you buy any municipal bond, you should know its rating and what that rating means for your money.

The second factor is what backs the bond. Some bonds are backed by the issuer's general tax revenue — these are called general obligation bonds. Others are backed only by the revenue from a specific project, like tolls on a new highway or fees from a water system. A general obligation bond is usually safer because the issuer has more ways to raise money if one revenue source fails. A revenue bond is only as safe as that one project.

Key Takeaways

  • Municipal bonds backed by general tax revenue are typically safer than those backed by a single project's income, because the issuer has more ways to raise money if one source fails.
  • The bond's credit rating — AAA, AA, A, BBB, or lower — tells you the risk that the issuer will not pay you back on time or in full.
  • Some municipal bonds are insured by a third party, which means that insurer promises to cover your payments if the issuer cannot, though this insurance itself has limits and conditions.
  • Municipal bonds can lose value if interest rates rise, even if the issuer never defaults, because older bonds paying lower rates become less attractive to buyers.
  • A few municipal issuers have defaulted on bonds in recent decades, most often when a single industry or employer dominated the local economy and that industry collapsed.

What happens when a municipal issuer runs out of money

When a city or county cannot collect enough revenue to pay its bonds, it has limited options. Unlike a private company, it cannot straightforward declare bankruptcy and walk away — state law usually requires the issuer to keep paying bondholders even if it means cutting services or raising taxes. However, some issuers have defaulted, meaning they stopped making payments on schedule or paid less than promised.

The most famous recent example is Detroit, which defaulted on municipal bonds in 2013 after decades of population loss and declining tax revenue. Bondholders recovered roughly 74 cents on the dollar after a bankruptcy process. Other notable defaults include Stockton, California (2012) and Vallejo, California (2008). These are rare — the vast majority of municipal bonds are repaid in full — but they show that default is possible, especially in cities or regions facing long-term economic decline.

When an issuer does default, the order of repayment matters. General obligation bonds, which are backed by the issuer's full taxing power, are usually paid before revenue bonds. Insured bonds are paid by the insurer before uninsured ones. But in a severe default, even senior bondholders may not recover their full investment.

How credit ratings predict payment risk

A municipal bond's credit rating is a prediction of how likely the issuer is to pay you back on time and in full. The three major rating agencies use similar scales. AAA and AA bonds are considered investment-grade and very safe. A, BBB, and BB bonds are still investment-grade but carry increasing risk. Anything below BB is considered speculative — meaning there is a real chance the issuer will not pay.

The rating is based on the issuer's financial history, the stability of its revenue sources, the size of its debt relative to its income, and the health of the local economy. A wealthy suburb with stable property tax revenue and low debt will get a high rating. A declining industrial city with shrinking tax revenue and high debt will get a low rating. The rating can change if the issuer's finances improve or worsen.

You can find a bond's rating on the bond's official statement, which the issuer publishes before selling the bond. You can also search for it on the Municipal Securities Rulemaking Board's EMMA database, which is free and open to the public. Before buying any municipal bond, check its rating and read the issuer's financial statements to understand why it received that rating.

The difference between general obligation and revenue bonds

A general obligation bond is backed by the issuer's promise to use all available revenue — property taxes, sales taxes, income taxes, and other sources — to pay you back. If one revenue source fails, the issuer can raise another. This makes general obligation bonds safer, and they typically carry higher credit ratings and lower interest rates than revenue bonds.

A revenue bond is backed only by the income from a specific project or service. A toll road bond is backed only by toll revenue. A water system bond is backed only by water fees. A hospital bond is backed only by hospital patient revenue. If that revenue source dries up — because traffic drops, water demand falls, or the hospital loses patients — the issuer may not be able to pay you. Revenue bonds carry higher risk and typically pay higher interest rates to compensate.

Some revenue bonds are backed by essential services that are unlikely to disappear, like water or sewer systems. These are relatively safe. Others are backed by discretionary services or projects that depend on economic conditions, like parking garages or sports stadiums. These carry much higher risk. When comparing two municipal bonds, always check whether each is a general obligation or revenue bond, and if it is a revenue bond, understand what revenue backs it.

Bond insurance and what it actually covers

Some municipal bonds are insured by a third-party company that promises to cover your interest and principal payments if the issuer defaults. The most common insurers are Ambac, MBIA, and Assured Guaranty. If a bond is insured, the insurer's credit rating becomes as important as the issuer's rating, because the insurer is now responsible for paying you.

Bond insurance sounds like a safety net, but it has limits. The insurer only covers the specific bond you own — it does not cover losses if the bond's value drops because interest rates rise. The insurer also has its own financial limits. During the 2008 financial crisis, some bond insurers ran into trouble themselves and could not cover all the defaults they had promised to insure. Before relying on bond insurance, check the insurer's own credit rating and financial health.

Insurance also costs money. An insured bond pays a slightly lower interest rate than an uninsured bond from the same issuer, because the insurance reduces the buyer's risk. Whether that trade-off is worth it depends on your confidence in the issuer and your need for extra safety. For a high-quality issuer with a strong rating, insurance may not be necessary. For a lower-rated issuer, insurance can make the bond safer.

Interest rate risk and how it affects bond prices

Even if a municipal issuer never defaults, the value of your bond can drop if interest rates rise. Here is how it works: suppose you buy a municipal bond paying 3 percent interest. If interest rates rise and new bonds are issued paying 4 percent, your 3 percent bond becomes less attractive to other buyers. If you try to sell it before it matures, you will have to accept a lower price to make up for the lower interest rate.

This is called interest rate risk, and it affects all bonds equally — safe ones and risky ones. The longer the bond's maturity, the bigger the price drop when rates rise. A 30-year bond will lose more value than a 5-year bond if rates go up by the same amount. If you plan to hold the bond until maturity, interest rate risk does not matter, because you will get your full principal back. But if you need to sell before maturity, rising rates will cost you money.

This risk is separate from default risk. A very safe municipal bond can still lose value if rates rise. Conversely, a risky bond might gain value if rates fall. When evaluating a municipal bond, think about both risks: the risk that the issuer will not pay you, and the risk that you will not be able to sell the bond for what you paid if you need the money before maturity.

Economic conditions that increase default risk

Certain economic patterns make a municipal issuer more likely to default. A city or region that depends on a single industry — like a coal mining town or an auto manufacturing hub — is at higher risk if that industry declines. A city with a shrinking population loses tax revenue as residents leave. A city with high unemployment cannot collect as much income tax. A region hit by a natural disaster may lose property tax revenue as property values drop.

Pension obligations also matter. Some cities have promised large pensions to retired workers but have not set aside enough money to pay them. As the retired population grows and investment returns disappoint, the pension liability grows. This can force the city to cut other services or raise taxes, which can trigger more population loss and further revenue decline. Before buying a municipal bond, research whether the issuer faces any of these long-term economic headwinds.

You can find this information in the issuer's official statement, which is published before the bond is sold and is available on the EMMA database. The statement includes the issuer's financial history, economic data about the region, and a list of major employers. If the issuer depends heavily on one employer or industry, or if its population and tax base have been shrinking, that is a warning sign that the bond carries higher risk than its credit rating alone might suggest.

How to research a municipal bond before buying

Start with the bond's official statement, which the issuer publishes and which is available free on the EMMA database at emma.msrb.org. The official statement includes the bond's rating, the issuer's financial statements, economic data about the region, and a detailed explanation of what backs the bond. Read the section titled "Risk Factors" — it lists the issuer's own concerns about its ability to pay.

Check the issuer's credit rating on the rating agencies' websites or on EMMA. Understand what the rating means: AAA and AA are very safe, A is safe, BBB is acceptable but carries some risk, and anything below BBB carries significant risk. If the bond is insured, check the insurer's rating as well. If the bond is a revenue bond, understand what revenue backs it and whether that revenue source is stable or vulnerable to economic changes.

Look at the issuer's financial history. Has it consistently collected enough revenue to pay its debts? Has its population and tax base been growing or shrinking? Does it have large unfunded liabilities, like pension obligations it has not fully funded? Does it depend on one major employer or industry? These factors do not appear in the credit rating but can predict whether the issuer will face financial stress in the future.

Frequently Asked Questions

Can a municipal bond issuer go bankrupt?

Yes, but it is rare. Municipal issuers can file for bankruptcy under Chapter 9 of the U.S. Bankruptcy Code. Detroit, Stockton, and Vallejo all did so in the past 15 years. In bankruptcy, the issuer and its creditors negotiate a plan to repay debts. Bondholders may recover less than they are owed, but they usually recover something. General obligation bondholders are typically paid before revenue bondholders.

What is the difference between a municipal bond and a Treasury bond?

A Treasury bond is issued by the federal government and backed by the full faith and credit of the United States. Default is extremely unlikely. A municipal bond is issued by a local government and backed only by that government's revenue and taxing power. Municipal bonds carry more default risk but typically pay higher interest rates. Treasury bonds are considered the safest bonds available.

Do I have to pay federal income tax on municipal bond interest?

No. Interest from most municipal bonds is exempt from federal income tax. Some municipal bonds are also exempt from state and local income tax if you live in the state that issued them. This tax advantage is why municipal bonds pay lower interest rates than taxable bonds of similar safety. The tax exemption does not affect safety — it just means you keep more of what you earn.

What happens to my municipal bond if the issuer is downgraded?

If a rating agency lowers the issuer's credit rating, the bond's value will drop because it is now considered riskier. If you hold the bond until maturity, you will still receive your full principal and interest payments on schedule, assuming the issuer does not default. But if you try to sell the bond before maturity, you will have to accept a lower price. A downgrade signals that the issuer's financial situation has worsened.

Are municipal bonds safer than stocks?

Generally yes. Stocks represent ownership in a company and can lose most or all of their value if the company fails. Municipal bonds represent a loan to a government, backed by a legal obligation to repay. Even if a municipal issuer defaults, bondholders usually recover some of their money. However, municipal bonds carry real default risk, especially lower-rated bonds, and they can lose value if interest rates rise. Neither is risk-free.