When we heard that Governor Weld was proposing eliminating the state income tax for those making less than $75,000 a year, we asked whether that would eliminate all state income tax for everyone on their first $75,000 in income or whether the tax break would apply just to those earning less than $75,000. The initial answer we received was that it was the former, which struck as a terrifically bold tax cut on the model of the growth-oriented income tax cuts that President Bush implemented after taking office. Call it the Good Start tax plan. But an aide to Mr. Weld, who is running as a Republican for governor of New York, later clarified that it is the second, meaning that Mr. Weld’s tax-cutting program is off to a bad start. Call it the Bad Start tax plan.

It means that the former Massachusetts governor has failed to think this through. Or take into account the fact that in tax policy, the details matter. Imagine, for simplicity’s sake, a state income tax of 10%. Under the Good Start plan, an earner with an income of $80,000 a year would pay an annual state tax of $500. There’d be no tax on the first $75,000, and the $5,000 in income above $75,000 would be subject to a 10% tax. The plan has a negative element, in punishing the New Yorker for earning income, but at least the earner doesn’t have to pay tax on his first $75,000.

Compare that to the Bad Start tax plan that the Weld aide clarified is what the governor is proposing in New York. Under that plan, the earner making $80,000 a year is subject to income tax on the whole thing – $8,000 in tax. After paying the tax, he’s left with only $72,000. Meanwhile, someone earning $74,000 would pay no taxes at all under the Bad Start plan. The Bad Start plan would essentially set a marginal tax rate – i.e., the tax on the next dollar earned – of more than 100%, discouraging a crucial band of New Yorkers from working overtime, starting small businesses on the side, or going back to school to increase their earnings. Why work the extra hours to get from $74,000 to $80,000 if the state income tax man is going to take all your money?

The Bad Start plan could also create a fierce family-unfriendly marriage penalty. Two single earners making $40,000 each under the Bad Start Plan would each pay no state income taxes, but if they got married and combined their finances they’d face a new tax bill of $8,000. It’s such a disincentive that it’s hard for us to see why Mr. Weld would prefer the Bad Start tax plan to the Good Start tax plan. It could be that he’s afraid of the plan being attacked as a giveaway to the rich. But President Bush breasted that criticism and got his own plan through. And in fact the benefits of even the Good Start Plan are tilted toward the poor and middle classes, especially in comparison to a truly growth-oriented plan such as a flat tax.

It could be that Mr. Weld is worried about his leading rival for the Republican nomination, John Faso. Mr. Faso was quoted yesterday by the AP as saying, “I’m all for tax cuts but it has to be in the context of a balanced budget.” Mr. Weld, who as governor of Massachusetts balanced every one of his budgets, would be making a mistake to be pushed into Mr. Faso’s approach. Let the taxes of New York first be brought to a level that are not the nation’s highest, and then let the state’s spending be set accordingly. Let, in other words, the household budgets of individual New Yorkers take precedence over the spending pool that is dispensed by lawmakers in Albany.

Our own hope is that Mr. Weld just was speaking off the cuff and hadn’t really thought the issue through. Mr. Weld is one of the most intelligent politicians we have met, and he’s fine on his feet. But on taxes, the key principle is to create growth by lowering marginal tax rates and increasing incentives to work, save, and invest. Shifting New York’s income tax burden entirely onto those who make more than $75,000 a year without giving them their share of the tax relief would be a Bad Start that would only hasten the stampede of New York’s high earners toward tax havens like Connecticut, New Jersey, or Florida.