More than half of CPA financial planners say their wealthy clients are not confident in the stock market, according to a survey by the American Institute of CPAs.

Nearly three quarters of the 421 CPA financial planners polled said their clients have grown more risk averse in their investment decisions in the past year. Sixty-two percent reported that retirement-age clients are postponing retirement from one to five years.

“Regardless of net worth, every American has to make it a priority to understand how the prevailing economic climate, whether it’s good or bad, affects individual personal finances,” said Clark M. Blackman II, chair of the AICPA’s Personal Financial Planning Executive Committee, in a statement. “This new survey of CPA financial planners shows that wealthy investors still feel nervous about the stock market and are being conservative in their investment decisions.”

The temporary suspension of the estate tax isn’t spurring many wealthy clients to take action on their estate plans, especially with speculation that Congress at some point this year may reinstate the tax retroactively. A large majority of CPA financial planners, 82.3%, said their clients are taking a wait-and-see attitude toward estate tax planning.

Financial means notwithstanding, high-net-worth clients have reduced their spending. A total of 87.3% of respondents said their clients were either spending slightly or significantly less.

Fifty-eight percent of the CPAs surveyed reported that anticipation of higher future tax rates was most likely to trigger 2010 conversions of traditional individual retirement accounts to a Roth IRA. Nearly as many, 54%, say they are advising clients to pay tax on Roth IRA conversions in 2010 despite an IRS allowance that allows taxes to be paid over three years.

Three quarters of the survey respondents, 75.8%, said the average net worth of their clients was between $500,000 and $5 million.