A battle is brewing over how much the Massachusetts Bay Transportation Authority can raise fares in the future, after Governor Charlie Baker moved to allow it to increase individual fares higher and more often than the Legislature wants.
The drama is unfolding in discussions over the state budget, during which the Legislature has sought to limit price hikes for each ride or monthly pass to 7 percent every two years.
But tucked into the amendments that Baker sent to the Legislature last week was a change in that proposal: The T would be able to increase some individual ride or pass prices higher than 7 percent every two years as long as the average increase didn’t surpass 7 percent overall. He also moved to allow the transit system to raise fares more than once every two years.
The MBTA says current state law allows it to increase fares up to an average of 10 percent every two years. This month, it raised fares an average of 9.3 percent — including some specific fares that increased more than 10 percent.
Jacquelyn Goddard, a spokeswoman for the state Department of Transportation, said the change would allow the MBTA to continue its current practice of increasing some fares at a higher rate to offset other fares that stay low or even decline.
In his budget amendment, Baker said that allowing the T to limit each individual fare or pass increase to 7 percent every two years would “impair the MBTA’s ability to ensure that appropriate steps are taken to deliver the reliable transit system that riders deserve.”
The budget amendment was first reported by the State House News Service.
But Rafael Mares, a senior vice president of the Conservation Law Foundation, said the governor’s change would take away the predictability that legislators want for riders.
Under the Legislature’s language, riders would know to expect a hike no higher than 7 percent every two years.
With the governor’s language, some commuters could see an increase of more than 7 percent for the fares or passes they use, and the hikes could come at any time.
“The idea is to make it so that it’s expected, and people can plan for it, and there isn’t a shock to the system,” he said. “People do plan how to spend their money, and it’s hard for them to adjust when those changes happen in an unpredictable fashion.”
State Senator Thomas M. McGee, a Lynn Democrat who cochairs the joint transportation committee, echoed the comments, saying that senators stand by the language in the legislation they gave to the governor.
“It’s important that the riders can count on the budget for a reasonable, moderate, and predictable fare increase going forward in the future,” he said.
Seth Gitell, a spokesman for House Speaker Robert DeLeo, said the House was reviewing Baker’s amendment.
The T interprets current law to mean that fares can be increased by an average that does not surpass 10 percent, using a complicated method that takes into account how much the various types of fares and passes are used. That translates into different increases for different fares and passes.
While an individual bus ride on a CharlieCard went up this month by 6.25 percent to $1.70, for example, student monthly passes went up 15 percent, to $30 a month from $26.
One fare went down, with cash bus rides dropping from $2.10 to $2.
Baker’s amendment would lower the current limit of a 10 percent average to 7 percent, using current methods for calculating the fare increase.
The fare hike law has been controversial since it was passed in 2014. At the time, senators believed they had limited increases to 5 percent every two years. But after the legislation came out of a conference committee, the law said it would limit fare hikes to 10 percent every two years.
When the MBTA last year began looking at fare changes, Transportation Secretary Stephanie Pollack and the T’s general counsel, John Englander, pointed to that law to justify raising fares higher than 5 percent.
They also said officials were able to increase the prices for some passes more than 10 percent because monthly passes are not legally fares, but “discounts” from fares.
That led some senators to cry foul.
In response, the Senate passed an amendment in the budget that would lower the fare hike limit to 5 percent every two years, the cap some senators said they believed they had already enacted.
When the budget went into a conference committee, lawmakers changed that language to include a 7 percent limit.
The language also made it clear that no single fare could be increased by more than 7 percent every two years.
Nicole Dungca can be reached at nicole.dungca@globe.com. Follow her on Twitter @ndungca.