Opinion

Can we trust Bill de Blasio’s numbers?

Today Mayor de Blasio will give us his hopes and priorities when he presents his first executive budget.

Here’s the question: Can New Yorkers trust his numbers? Even the liberal New York Times is unsettled by the new mayor’s fondness for making big promises:

“From the pledge of billions of undefined health care savings in its newly struck deal with the teachers’ union, to its plan to reduce traffic deaths (in a city of eight million) to zero, [the de Blasio administration] has spun the dial on expectations well past 11,” a Times editorial frets.

The paper’s skeptical — not just because de Blasio’s plans often lack detail, but because they seem based on wishful thinking.

Take the deal with the teachers union. The mayor OK’d raises of 18 percent over nine years, costing billions. We now know none of it will come from union concessions — e.g., teachers chipping in for their health-insurance premiums.

“Health-care benefits [were] preserved with no additional costs to members,” boasted the office of teachers-union boss Mike Mulgrew.

Rather, the raises will be funded, in part, by unspecified “savings” in health-care costs the mayor hopes will materialize. Moody’s, the credit-rating agency, says the agreement “could increase future budget gaps to levels that would be more difficult for the city to deal with, especially during another downturn.”

Ditto for de Blasio’s 10-year housing plan. He says $41 billion will fund 200,000 below-market-rate units. But $30 billion is supposed to come from private developers — unless they opt out. Likewise for the $3 billion from Albany and Washington, which might never arrive. Even the city’s $8 billion share is uncertain.

True, several authorities — the city and state comptrollers, the Independent Budget Office, the state Financial Control Board — can vet de Blasio’s numbers, including his revenue estimates and financing schemes. We have to hope they will do their duty faithfully, without regard to politics.

New Yorkers will surely learn much today about the mayor’s ambitions. It may be some time before anyone knows if they’re realistic.