Investors have a new way to invest in municipal bonds. The American Recovery and Reinvestment Act of 2009 authorized a subsidy for local and state governments that issue what are known as Build America Bonds (BABs) before January 1, 2011.

Unlike most municipal bonds, the interest payments you receive on a BAB are taxable on your federal income tax return. However, the federal government subsidizes 35% of those interest payments. That subsidy is made in one of two ways:

1. As a direct payment to the governmental body that issued the BAB, or
2. Via a 35% federal income tax credit on the net coupon interest to the bondholder

The governmental body that issues a BAB determines in advance which type of subsidy it prefers; so far, most governmental bodies that have issued BABs have chosen to do so using the direct payment method rather than offering the tax credit.

If you're interested in tax credit bonds, don't assume the credit automatically makes them more valuable than a fully taxable bond. Because both the bond's interest payments and the value of the tax credit will be included in your gross taxable income, the calculation depends not only on the coupon rate but also on your tax bracket. It's best to check with your financial professional to compare a BAB to both taxable and tax-free municipal bonds to determine which is the better choice for you. Any unused portion of a BAB's tax credit may be carried forward to successive years.

Before investing, make sure you know if a given BAB offers the 35% tax credit, and what it would mean given your tax bracket. Also, remember that even though the federal subsidy is designed to help lower local governments' cost of financing projects, it does not mean that the bond is guaranteed by the U.S. government, as Treasury securities are.