That's right. If moving eliminates a 14.8% top state and local tax rate, our top-tier taxpayer gets a 36% raise, not a 14.8% raise, by leaving. It's doubtful if any of our city and state leaders have done this math, but it's shocking.

Mamdani wants to take the top rate up another 2%, if not by the state then by the city, which would mean that our rich neighbor can get a 42% raise.

Here's how the math works.

A rich New Yorker pays a maximum state and city income tax of 14.8%, on top of a maximum federal tax of 37%. But there are hidden taxes. Uncapped Medicare and Medicaid taxes push the marginal federal tax to 39.4%. If the income is earned on investments, the Net Investment Income Tax (NIIT, another gift from Obamacare) adds another 3.8%, pushing the top federal tax above 43%.

So, top-tier New York taxpayers may soon pay a marginal tax of 43% to the IRS and 17% to the city and state of New York. The combined 60% marginal tax rates mean they have the privilege of keeping 40 cents of each new dollar they earn. A move to one of the nine states with no income tax allows our taxpayer to keep 57% of every additional dollar of income, instead of 40%. Do the math. That's a 42% raise.

Forget the argument about "paying their fair share." "Fair" is an entirely subjective term. Your fair share of someone else's money might be seen as a ripoff by them, especially if the money is spent less wisely than we might spend our own money. If you are rich and believe you've earned your money, will you consider leaving a state for a permanent 40% raise? Of course.

This is hardly a phenomenon unique to New York. California's headline top rate of 13.3% becomes 14% with the phase-out of deductions. A Silicon Valley billionaire can keep 43% of each new dollar of income. Moving to Dallas or Miami, or Anchorage for the adventuresome, boosts this to 57%, a raise of almost 33%. This doesn't even count the "please leave now" impetus of a "one-time only" 5% wealth tax on billionaires. Never mind that the fine print on the wealth tax initiative turns a 5% tax into a 50% expropriation for billionaires like the founders of Google, because their 30% voting share at Google, not their 3% equity ownership, is used to determine the tax.