From the Wall  Street Journal.com:
Here's a two-minute drill in soak-the-rich  economics:
Maryland couldn't balance its budget  last year, so the state tried to close the shortfall by fleecing the  wealthy. Politicians in Annapolis created a millionaire tax bracket,  raising the top marginal income-tax rate to 6.25%. And because cities  such as Baltimore and Bethesda also impose income taxes, the state-local  tax rate can go as high as 9.45%. Governor Martin O'Malley, a dedicated  class warrior, declared that these richest 0.3% of filers were "willing  and able to pay their fair share." The Baltimore Sun predicted  the rich would "grin and bear it."
One year later, nobody's grinning. One-third  of the millionaires have disappeared from Maryland tax rolls. In 2008  roughly 3,000 million-dollar income tax returns were filed by the end  of April. This year there were 2,000, which the state comptroller's  office concedes is a "substantial decline." On those missing  returns, the government collects 6.25% of nothing. Instead of the state  coffers gaining the extra $106 million the politicians predicted, millionaires  paid $100 million less in taxes than they did last year -- even at higher  rates.
No doubt the majority of that loss in  millionaire filings results from the recession. However, this is one  reason that depending on the rich to finance government is so ill-advised:  Progressive tax rates create mountains of cash during good times that  vanish during recessions. For evidence, consult California, New York  and New Jersey (see here).
The Maryland state revenue office says  it's "way too early" to tell how many millionaires moved out  of the state when the tax rates rose. But no one disputes that some  rich filers did leave. It's easier than the redistributionists think.  Christopher Summers, president of the Maryland Public Policy Institute,  notes: "Marylanders with high incomes typically own second homes  in tax friendlier states like Florida, Delaware, South Carolina and  Virginia. So it's easy for them to change their residency."
 
