The MTA is ordering its bus drivers not to automatically open their vehicles’ rear and center doors for customers — to try to thwart free-loading scofflaws, The Post has learned.

“Effective immediately, to deter fare evasion,” agency drivers cannot “use the rear door toggle switch to open the rear/center automatically, unless it is necessary due to an emergency situation,” says a May 6 memo sent to all MTA bus operators.

The new directive will ideally force potential fare beaters to enter through the front doors of the bus — and be confronted by the driver if they don’t pay.

It also means bus riders will have to manually activate the rear and center doors themselves if they want to exit through them.

The back and center doors on the MTA’s express “Select Bus Service” routes will continue to open automatically at all stops, the memo said.

“The policy is intended to continue to offer customers easy exits while deterring fare evasion by reducing the time that rear doors are open while no one is exiting on local bus routes,” MTA spokesman Aaron Donovan said in a statement to The Post.

MTA CEO Janno Lieber last month pledged to tackle soaring subway crime partly by setting up a review panel to figure out how to curb fare evasion, which has jumped on both buses and subways during the COVID-19 pandemic.

Nearly 30 percent of city bus riders aren’t paying their way, according to the MTA’s latest fare-evasion survey — up from just over 20 percent at the end of 2019.

But J.P. Patafio, vice president for Transport Workers Local 100’s Brooklyn bus division, called the memo “silly” because drivers rarely open bus back doors themselves, anyway.

He said he hoped the implication would not be that bus operators should haggle for fares, which has led to driver assaults in the past.

“If somebody is coming through the back door, it’s usually because there’s a lot of people getting off the bus,” he said. “The bus driver’s job is already very difficult, and we already know that enforcing fares leads to assault and fights on the bus.”

The MTA’s new directive defies its long-term goal of implementing all-door entry and fare collection on all its buses. OMNY tap-and-go card-payment readers have been installed on all buses but are currently only turned on for Select Bus routes.

Lieber last month told reporters it was too soon to turn on the rear-door OMNY readers because the vast majority of bus riders still pay with MetroCards or cash.

“I think we only have somewhere between 10 and 15 percent OMNY penetration on the buses,” he said. “It wouldn’t really be fair to try to manage rear-door bus boarding and limit it to OMNY customers.”