It turns out the new Tappan Zee Bridge may well be over-budget after all — which would be entirely appropriate for a span officially named after big-spending former Gov. Mario Cuomo.

Politico reports that contractors are getting set to submit $900 million in claims for added expenses on the project, to cover change orders, overtime and other labor charges that they say the state is obliged to pay.

That would push the total over the $4 billion that Gov. Andrew Cuomo described as the high-end cost, and end his bragging that he’d gotten the job under budget.

To be fair, Cuomo at least got the thing built — a badly needed project that other governors had merely talked about for decades. On the other hand, he’s never explained in full just how he’s paying for it, beyond devoting some of the state’s windfall from bank legal settlements to cover half the $4 billion cost.

Then again, he never actually committed to a specific hard figure for the cost, so it’s hard to say if any of the coming contractor claims are truly unexpected.

“At the end of the day, we don’t really know what’s an overrun and what isn’t an overrun, because the governor was never clear about what the true cost of this bridge was going to be,” Brian Sampson, executive director of the Associated Builders and Contractors, told Politico.

Plus, the contracts prevent the builders from discussing the basis for their new cost claims with the media. That gag order is of a piece with the gov’s penchant for secrecy on this and countless other projects.

For now, the Thruway Authority has budgeted $459 million this year and $343 million more in 2019 on the project. But the payments on roughly $2 billion in loans for the bridge don’t start until long after that, and the agency hasn’t yet explained how it will come up with that cash.

Cuomo is still pretending that it won’t require toll hikes — on the bridge, and possibly across the Thruway system — but that’s long been the only real possibility.

In a way, that makes his achievement even more impressive: He has sold New Yorkers a bridge without ever telling them how much they’d have to pay.