While Congress was passing the landmark federal tax cut law on Wednesday, Gov. Chris Christie was offering an answer to New Jersey critics of its limit on the deduction of state and local taxes.

Starting next year, people can’t subtract all of their state and local taxes, including on property, from their income subject to federal tax. The Republicans’ $1.5 trillion federal tax overhaul will only allow a combined $10,000 deduction for such taxes.

Most people in the state don’t pay enough state and local taxes to make the itemized deduction of them worth more than taking the standard federal deduction.

Christie is a resident who does, and he said the state should respond to the federal $10,000 cap by letting residents deduct their property taxes in full on their state income tax returns. Currently they can only deduct up to, yes, the same $10,000 limit now allowed by the federal government.

The governor said his property taxes are $41,000 a year. Now, instead of deducting that whole amount on his federal 1040, he’ll be limited to $10,000.

“So now that’s $31,000 in additional taxes that I’m paying just on the property taxes,” Christie said.

But it’s not. If Christie did his own tax return, he would know that the $31,000 is an increase not in his tax due but in his taxable income. The resulting additional tax would be about a quarter of that, or $7,750.

Even that smaller amount would be only partly offset by the increased property tax deduction he proposes for state income tax returns. Since the state tax rate is about a third of the top federal income tax rate, an increased deduction would only provide one-third relief.

The new federal limit on deducting state and local taxes will fall hardest on the wealthiest New Jersey residents. And those making more than $1 million a year were already targeted by Gov.-elect Phil Murphy for a new tax to raise $600 million to fund public education and reduce property taxes.

Senate President Stephen Sweeney said this month he’s worried about the impact of this potential double hit on the state’s high-income earners. He said he’ll appoint a task force to assess the impact of the federal tax cuts and then decide whether the Legislature should go forward with the millionaire’s tax.

Maybe Christie’s proposed state deduction could be part a deal to make the millionaire’s tax more palatable, which would be funny since Christie is an ardent foe of the millionaire’s tax and vetoed it five times. The state treasurer told him the higher property-tax deduction would reduce revenue by about $160 million, about a quarter of what the millionaire’s tax would bring in.

None of these tax issues affect average residents directly. But now even the Democrats are worried that taxes on the richest residents might cause them to flee the state, taking their businesses, spending and tax payments with them. That would hurt everyone.

The answer might be to give top earners something they want in return for shouldering an even bigger share of the tax burden, such as a solid commitment to reducing spending and the size of state government. A new tax plus a spending cut would do more to stabilize New Jersey’s finances and be fairer to the middle-class residents, whose taxes are the highest percentage of their income.