Once you become a millionaire, the odds are stacked against your staying one. The Tax Foundation points out in a new study that millionaire status is fleeting, with a significant level of turnover. Over a nine-year period, a full 50 percent of taxpayers filed as millionaires for one year, and an additional 15 percent were millionaires for two years. Only 6 percent were millionaires for the entire nine years.


Why is millionaire status so fleeting? Millionaire taxpayers draw a significant amount of their money from small businesses that are taxed as individual income, as well as from capital gains -- two sources that are relatively volatile.

But while membership in the millionaire's club may be ephemeral, there are certain characteristics of the group that hold constant over time: Members "are typically married (and most of them are two-earner couples), they are highly educated, many are business owners, and nearly half are over the age of 55," the Tax Foundation reports.