Investors are creatures of habit, especially when their habits have produced consistently rewarding results with low risk. An example is the deep attachments some of your clients have formed over time with tax-exempt municipal bonds and bond funds. You may have clients who couldn't be pried from their munis with a crowbar.

But now may be the time to try – or at least to suggest a thorough review of muni holdings and clients' objectives.

According to the Securities Industry and Financial Markets Association, the U.S. muni market consists of bonds worth $2.4 trillion, of which more than two-thirds ($1.7 trillion) is held by individuals or mutual funds. This is the largest debt market in the world dominated by individuals. For decades, it has worked with machine-like consistency to help high-income individuals achieve personal goals, including tax-free retirement income.