The state's plan to upgrade Penn Station through a sprawling redevelopment project could ultimately leave taxpayers on the hook for billions of dollars, according to a new analysis.

Economists hired by Reinvent Albany, a government watchdog group, say the project may only raise enough money from commercial leases in the nine new office towers and one residential property to cover nearly half of the estimated $10 billion price tag for Penn Station and eight acres of public space surrounding it. The release of the report comes amid ongoing concerns voiced by lawmakers and advocates over whether the state has a firm financial plan to fully fund the project.

With the state providing few details on the project’s financing plan, economists applied a similar model used to fund the Hudson Yards project. There, revenue for the project was funded through so-called payments in lieu of taxes (PILOTs), with an additional 20% tax discount. Applying that formula to the Penn Station project, economists found the deal would ultimately generate $4.1 billion, not $10 billion, while providing a $1.2 billion tax break, mainly to developer Vornado Realty Inc. The firm will build the majority of new buildings surrounding Penn Station.

With such a shortfall, economists say the state will have to look for upwards of $5.9 billion from other sources, including state-backed loans that would ultimately be bankrolled by taxpayers. Leaders of the Empire State Development Corporation, which is managing the project, have said there would be other fees charged to developers, but it hasn’t outlined what they’d be or how much revenue they would generate.

The analysis was conducted by Bridget Fisher, an economist at the Schwartz Center for Economic Policy Analysis at the New School, who said her work doesn’t factor potential shortfalls from other things, like a recession or if the commercial real estate market doesn’t bounce back.

“Unfortunately, there’s no details about how these risks are anticipated to be managed," Fisher said. "And if that’s not baked in up front then what happens in these projects is the taxpayers have to foot the bill in the end."

The state hasn’t provided a detailed financial plan for the project. But Matthew Gorton, a spokesperson for Empire State Development, says Midtown could use the improvement. He added the project would help “unlock the real value of the long-neglected area.”

“It’s disappointing that an organization that considers itself a citizens’ watchdog would prefer Penn Station remain a junkyard, denying New Yorkers the significant affordable housing, open space and desperately needed transit improvements this plan provides,” Gorton wrote in a statement.