According to an internal memo from the Port Authority of New York and New Jersey, taking a taxi, Uber, Lyft or limo to and from a New York-area airport could soon cost $4 more per trip.

A plan outlines a hike in fees on airport pick-ups and drop-offs at John F. Kennedy International Airport, LaGuardia Airport and Newark Liberty International Airport — which are among the only airports in the country that don’t charge curbside access fees. The fee is similar to those charged at several other large U.S. airports like Los Angeles International Airport and Chicago O’Hare International Airport.

“The airport is maybe the most important source of income, especially for yellow cab drivers,” said Bhairvai Desai, director, New York Taxi Workers Alliance. “If you’re charging $4 per ride, there’s no doubt that will affect ridership and, at a minimum, tips will come down.”

Port Authority noted the revenue from the fees will be used for airport improvements like a new taxi dispatch system. The fee would be charged to the car operator and presumably passed to passengers.

Representatives for the taxi industry and Uber criticized the proposal saying it would add to the cab fares and cause a reduction in tips. Lyft, however, backs the proposal. The app spokesman Adrian Durbin said the company favors the deal because it would mean an agreement is in place guaranteeing the app to operate at New York’s airports.

The new fee is still in the proposal stage and not yet policy.