Taxability In the United States, although not all municipal bonds are tax-exempt, most are. Tax-exempt securities represented about 80% of trading volume in U.S. municipal bonds in 2020. Interest income from most municipal bonds is excludable from gross income for federal income tax purposes, and may be exempt from state income tax as well, depending on the applicable state laws. Internal Revenue Code section 103(a) is the statutory provision that excludes interest on municipal bonds from federal income tax. , other rules, however, such as those pertaining to private activity bonds, are found in sections 141–150, 1394, 1400, 7871. The state and local exemption was the subject of litigation in
Department of Revenue of Kentucky v. Davis. Bonds issued for certain purposes are subject to the alternative minimum tax as an item of tax preference.
Liquidity Historically, municipal bonds have been one of the least liquid assets on the market. One indicator of this is their infrequent trading. Municipal bonds are actively traded in a "when issued" market, and also immediately after they are issued. Once the bonds find their way into retail and mutual fund portfolios, the volume of trade drops off dramatically. The MSRB reports that from March 1998 to May 1999, 71% of the outstanding issues did not trade at all. A 2005 study concluded that 4–6 months after issuance, less than 10% of the sampled bonds traded at all; the probability then rises somewhat so that by four years from issuance, roughly 15% of the bonds in the sample traded at least once during a given month. A 2007 study concluded that the average investment grade tax exempt 1-10 year municipal bond traded 21 times over its 11-year sample and 5.65% of issues only traded once. Unlike corporate and Treasury bonds, which are more likely to be held by institutional investors, municipal bond owners are more diverse, and hence harder to locate, giving this market less liquidity. Compared to stocks, municipal bonds are much harder to maneuver. At the same time, the minimum investment amounts for stocks are typically <$500 and about $1000 for CDs and money markets; in comparison, municipal bonds typically have minimum denomination buy-ins of $5000 but smaller issuers may have buy-ins of $1000 to incentivize local or regional investors. To put this into context, there are ~4300 US domestically incorporated exchange-listed stocks and 10,500 stocks that trade
over-the-counter. Over the last decade, technology solutions have been applied to make the market more responsive to investors, more financially transparent and ultimately easier for issuers and buyers. The emergence of small denomination municipal bonds makes the muni market more accessible to middle-income buyers. It is believed that these initiatives will reduce lower debt issuance costs. Historical default rates have been lower in the municipal sector than in the corporate market. This may be due in part to the fact that some municipals are backed by state and local government power to tax, or revenue from public utilities. However, sharp drops in property valuations (as in the
2009 mortgage crisis) can strain state and local finances, potentially creating municipal defaults. Harrisburg, PA, when faced with falling revenues, skipped several bond payments on a municipal waste to energy incinerator. The prospect of municipal bankruptcy was raised by the Controller of Harrisburg, although it was opposed by Harrisburg's mayor. Default risk to the investor can be greatly reduced through municipal bond insurance, which promises to pay interest and principal if the issuer does not do so. ==Return analysis==