Big employers in the city may have to enroll in a federal commuter tax benefit program that transit groups say can help thousands of subway and bus riders save hundreds of dollars a year.

Councilman Dan Garodnick Sunday said he will introduce legislation Tuesday requiring employers with 20 or more workers to sign up for a federal transit tax benefit.

A business that offers the benefit uses a worker's pre-tax pay, of up to $130, to cover a MetroCard. The employee benefits with a reduction in their taxable income.

A New Yorker who buys a $112 monthly unlimited MetroCard and makes the city's median income can save $443 a year, according to Riders Alliance, a grassroots transportation group.

"A lot of employers may not appreciate the benefit of the program to them or the benefit of the program to their employee," Garodnick said.

The Riders Alliance estimated there are a million people in the city who cannot access the tax benefit and that the legislation will make it available to more than 600,000 riders. The group also said employers can save with this program, as well, by getting a break in payroll taxes.

Councilman Ydanis Rodriguez, who chairs the transportation committee, lauded the proposal as a benefit to riders who face fare hikes next year. Rodriguez said he received the benefit as a former teacher and now as a city lawmaker.

“We know that the fare increase is something that will continue happening in the MTA,” Rodriguez said. “Bringing a program that makes transit affordable for everyone is the right thing to do.”