Municipal Tax-Free Bond Funds Municipal bond funds invest in the obligations of state and local government agencies. The interest income from municipal bond funds is generally exempt from Federal income taxes (although any capital gains would be subject to taxation). Investors who are taxed at one of the higher marginal rates generally will benefit by investing in a municipal bond fund rather than a taxable bond fund. If you buy a bond fund that limits its investments to the state in which you reside, you may earn income that is exempt from state and local income taxes as well. Like their taxable counterparts, tax-exempt bond funds are available in a range of maturity levels, including short-term, intermediate-term, and long-term. Most municipal bond funds purchase only investment-grade issues; some go one step further in credit quality, emphasizing municipal bonds that are insured by private insurance companies. There are also municipal bond funds that specialize in high-yield or lower quality municipal bonds, too.