The MTA is rolling out its tap-and-go fare-payment system at 48 more city subway stations next month — including Penn Station, officials announced Tuesday.

The swipe-free system, known as OMNY, lets riders pay their fares with a contactless credit card or mobile-phone wallet instead of swiping a MetroCard.

So far, only Staten Island buses and Lexington Avenue subway-line stations between Atlantic Avenue in Brooklyn and Grand Central Terminal in Manhattan are equipped with OMNY readers.

But that’s set to change big-time in December, the agency said. In addition to Penn Station, which serves six different transit lines, OMNY readers will be installed at the Whitehall Street and South Ferry train stations in Manhattan, 86th Street-Bay Ridge in Brooklyn, Sutphin Boulevard-Archer Avenue in Queens and St. George and Tompkinsville on Staten Island.

The new technology also will be installed at every No. 6 train stop between 51st Street and 125th Street in Manhattan, No. 4 train stops north of 125th Street and stops on the No. 1 train between Rector Street and Columbus Circle.

OMNY has been a smash hit with city users so far, the MTA says. New Yorkers and tourists from 111 countries have used OMNY a whopping 3 million times, according to the agency.

Moving ahead, the MTA plans to announce additional OMNY-compatible stations each month — with the full roll-out expected to wrap up next fall, according to MTA Chief Revenue Officer Al Putre.

The entire city bus system will have the technology by December, Putre said, followed by the Long Island Rail Road and Metro-North in 2021.

Public-transit riders will continue to be able to use their MetroCards until July 2023.

“The biggest complaint we get right now, and it’s been consistent: Everyone wants to know ‘when is OMNY coming to my bus line,’ ‘when is OMNY coming to my station,’ ” Putre told The Post.

“It’s real simple,” he said of its popularity. “It’s convenience.”