The socialite wife of 90-year-old Greek shipping magnate Spiros Milonas owes the Internal Revenue Service a whopping $2.27 million — and her estranged husband is refusing to pay her seven-figure debt.

Manhattanite Antonia Kotovos Milonas, 64, never paid the balance on her 2017 income taxes, so the IRS slapped a lien on her West 57th Street condo last month, records show.

Spiros Milonas, whose health is declining, had gifted his wife the $4.25 million apartment in apparently happier times in 2005.

The pair runs a real estate company together called Axios, but Spiros is unwilling to help out his wife with her tax debt, according to his longtime friend and adviser, John Catsimatidis.

“It is not Sprios’ responsibility,” the billionaire businessman told The Post in a phone interview last week.

“I am Spiros’ financial officer,” he said. “I have not authorized Spiros’ people to pay her IRS debts. It’s her responsibility, according to the marriage contract.

“They do file separate tax returns, and his taxes are up to date,” Catsimatidis added.

Antonia’s last public spat with her husband played out in 2017, when he filed a suit claiming she tried to boot Spiros from their home to hasten his death — and her inheritance.

Antonia, who “routinely yells and acts abusively towards’’ her husband, forced her feeble spouse to change their prenup to secure herself an $8.4 million payday, the suit claimed.

Spiros is worth an estimated $500 million, according to The Real Deal. The pair married nearly 20 years ago.

He made the troubling claims in the unusual lawsuit against his wife — but later withdrew the suit, saying it was filed by a lawyer without his permission.

The Greek-born businessman said at the time that he only learned about the lawsuit from a story in The Post.

“How did this happen? I was so surprised. We opened The Post, and we are there,” the then-88-year-old shipping tycoon said, referring to a photo of him and his wife that ran with the article.

Spiros said he suspected that his two adult daughters were behind the legal maneuver because “they are not happy that I remarried.’’

But the lawyer who oversaw the suit said Spiros “directed me to file it,’’ and the attorney for the Greek multimillionaire’s daughters insisted they had nothing to do with the move.

A source told The Post that Antonia and Spiros — whose past paramours included Joan Rivers — are still married but estranged.

In a recent court filing related to a lawsuit involving their real estate holdings, however, Antonia said they are still living together.

She did not return messages seeking comment.