Municipal Bonds

How it works

A state, city, county, school district or public authority issues bonds to build or refinance something concrete — a road, a hospital, a water system, a stadium — and repays bondholders with interest drawn from taxes or from the project's own revenue. The two structures split on that point. General-obligation bonds are secured by the issuer's full faith, credit and taxing power; some are further limited by statutory tax caps, and the official statement will spell out exactly which taxes stand behind the pledge.

Revenue bonds are payable only from a defined stream — water and sewer charges, toll receipts, airport landing fees, hospital revenue — with no recourse to the issuer's general tax base if that stream falls short. This distinction matters more than the label GO or revenue itself; the specific pledge and the covenants around it determine what happens under stress.

Interest is generally exempt from federal income tax under Section 103 of the Internal Revenue Code, and typically from state income tax for residents of the issuing state. Private-activity bonds, which finance projects with a substantial private user, are an exception: their interest can be a preference item for the alternative minimum tax. Taxable municipals, including the Build America Bonds program, also exist and trade without any exemption at all.

Issuers post official statements, audited financials and material-event notices on the MSRB's EMMA system, which is the market's primary public disclosure venue. Reading the official statement before buying, and then watching EMMA for updates, is the core of the ongoing work this asset class asks for.

What it pays

Municipal bonds are quoted as a yield to maturity or, when they are callable, a yield to worst — the lower of the yield to the first call date and the yield to maturity. Because the coupon is tax-free, munis carry lower nominal yields than Treasuries of comparable maturity; the number that actually matters for comparison is the taxable-equivalent yield, which grosses up the muni yield by the buyer's marginal tax rate.

The main drivers of that yield are the shape of the Treasury curve, the issuer's credit rating, the state of the tax code, and supply — a heavy new-issue calendar cheapens the whole market for a period. In-state buyers in high-tax states often accept a lower stated yield because the combined federal and state exemption is worth more to them, which is why single-state muni markets price differently from the national market.

Bond insurance from a monoline guarantor can lift a bond's rating and lower its yield, but the guarantee is only as strong as the insurer standing behind it — a fact the 2008 monoline crisis made explicit. Most municipal bonds are callable roughly a decade after issuance, a structural feature that caps upside when rates fall and is worth reading directly in the call schedule before buying.

Costs and taxes

Retail municipal bonds are typically bought with a dealer markup embedded in the price rather than a visible commission line. EMMA's post-trade price transparency makes those markups visible after the fact, which is the main check a buyer has on execution quality.

Interest is generally free of federal income tax and, in most cases, of the issuing state's tax for residents; it is still reported as tax-exempt interest on Form 1099-INT. Capital gains on a muni, by contrast, are fully taxable — the exemption covers the interest payment, not price appreciation. Buying a bond below par in the secondary market can also trigger the market-discount rules, which convert part of the eventual gain into ordinary income once it exceeds a de minimis threshold.

Tax-exempt interest is not invisible to the rest of the tax code: it is included in the calculation of how much of a Social Security benefit is taxable, and in the income measure used to set Medicare premium surcharges. Because the exemption is the whole point of the instrument, holding munis inside an IRA or 401(k) wastes it — the benefit only exists in a taxable account.

Liquidity and time commitment

The municipal market is large in aggregate but fragmented at the level of any single bond — hundreds of thousands of distinct CUSIPs exist, and most do not trade on a given day. Individual bonds can be sold through a dealer, but odd lots typically clear at a worse price than institutional-size blocks, a gap that widens for smaller or less-followed issuers.

Holding to maturity or to the call date avoids the liquidity question entirely, and it is the reason many buyers choose individual bonds in the first place. Funds and ETFs trade the fixed maturity date away for daily liquidity, which suits a different purpose. Ongoing effort for a direct bondholder is mostly passive — watching call notices and monitoring the issuer's continuing disclosures on EMMA — rather than active management.

How it goes wrong

Credit events are rare in this market but not theoretical. Detroit's 2013 bankruptcy and Puerto Rico's subsequent restructuring both imposed losses on bondholders, including some who had assumed general-obligation status made them effectively whole. Revenue bonds fail on a narrower path: the project's revenue falls short of forecast — a toll road with traffic below projections, a hospital that loses its service area, a stadium whose anchor tenant leaves.

Call risk works against reinvestment timing: issuers refinance when rates fall, returning principal at exactly the moment new bonds pay less. Liquidity risk compounds this on the way out — a bond that looked cheap to buy can be expensive to sell in a small lot.

Tax risk is particular to this asset class: an issue can lose its exempt status retroactively if the IRS determines the proceeds were not used as represented in the official statement, converting prior interest into taxable income for holders. Concentrating in a single state's bonds also concentrates exposure to one government's finances, one regional economy, and one public pension system, all of which move together in a downturn.