In a four-year period before the millionaire's tax, the aggregate net worth in the state increased by $98 billion, the report said. After the tax, the net outflow reversed "70 percent of the wealth gained in the prior four years," the report said.

The report , from the New Jersey wealth-management firm RegentAtlantic Capital, has been lighting up the New Jersey media and websites. It says that in 2010 alone, New Jersey lost taxable income of $5.5 billion because residents moved. It ties the wealth flight to the state's "millionaire's tax," which raised taxes on those making $500,000 or more (roughly the top 1 percent of New Jersey taxpayers) starting in 2004.

A new study says the wealthy are fleeing New Jersey for lower-tax states like Florida and Pennsylvania. But like many similar studies, it fails to prove a clear cause and effect between the movements of the rich and taxes.

The report is one of several studies in recent years analyzing New Jersey's high taxes on its wealthy. And it comes as some state Democrats push for even higher taxes on high earners. Aside from its high income taxes, New Jersey also has famously high property taxes, estate taxes and other local levies.

Several previous studies have echoed RegentAtlantic's assertion that high taxes are gutting New Jersey's wealthy population and tax revenue. Others, like this Princeton study, find no clear evidence that high taxes are chasing out the rich.

The RegentAtlantic report should be taken with some caveats. First, RegentAtlantic is a wealth management firm, so its interest is in protecting and preserving New Jersey's wealthy (or at least their existing clients). It says its paper relies on "anecdotal evidence," its own survey and a review of existing studies.

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But while the paper goes into a detailed argument on why tax migration makes financial sense, it states at the beginning that "this paper does not provide proof or hard evidence that high income and/or high net worth residents are leaving New Jersey because of high taxes."

Finally, it says the average adjusted gross income of the people leaving New Jersey for Florida is $74,000 a year. People making $74,0000 a year are not subject to the millionaire's tax—that only applies to $500,000 a year earners.

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Finally, while millionaires may be leaving New Jersey, the state is also creating new ones. A recent study found that New Jersey ranks second in the nation (after Maryland) for its millionaires per capita.

This is not to say New Jersey is thriving. The report points out that the high costs and restrictions to doing business in the state have been costly. But it remains unclear whether the millionaire's tax is the sole reason some of New Jersey's rich are moving to Florida.

—By CNBC's Robert Frank. Follow him on Twitter @robtfrank.

