After suffering through steep losses last year, municipal bonds and related exchange traded funds (ETFs) have been riding the wave of investment interest in the bonds sector.

Municipal bond mutual funds increased 14.4% on average through Oct. 29 and yields have not experienced their current lows in more than four decades, reports Jonathan Burton for The Wall Street Journal. The surge in muni bonds may be over, but some believe this investment vehicle still have a place in many portfolios, especially as tax time looms. (The current bond hot spots).

Many states face deep budget deficits, potential downgrade risk and headline risk. Bonds usually drop in price when credit ratings are bad or when budget deficits are high.

Still, muni bonds appeal to investors because of of their tax-free income status. Munis are generally exempt from federal and state level taxes. Their tax-free status will become more appealing as federal income taxes become higher as the Bush administration’s tax cuts expire at the end of 2010.

Currently, the supply/demand imbalance is supporting the price of municipal bonds. Professionals suggest potential investors stick to bonds with at least a single-A rating. They also note that long-term bonds are more susceptible to interest rate changes and don’t provide enough to compensate. (What you need to know about bond ETFs).