It's not illegal to swipe in riders with your MetroCard. View Full Caption DNAinfo/Trevor Kapp

MTA fare hikes went into effect Sunday — with the price of a monthly MetroCard increasing to $121 and a weekly jumping to $32.

But New Yorkers are still free to swipe in their fellow straphangers at turnstiles.

It’s not illegal to use your MetroCard to help another rider gain access to the system, the NYPD and the MTA said, as long as you’re not charging for the swipe. Jumping the turnstile is illegal, though.

Shit I'm shook I didn't know the fare hike started today...guess I'm hopping — Sarah Jonas (@_sarahjonas) March 20, 2017

First business day of MTA #farehike, watched 3 locals pass before I see an express. Now the express is on the local. Good start! — Krista M. (@kristuhh) March 20, 2017

In the past, fare-begging could've resulted in an arrest, but the city announced last year that it would take a more lax approach toward that sort of low-level criminal offense. Police can now give a ticket or summons to someone asking for a swipe instead of taking them into custody.

"By reducing unnecessary incarceration, we make our criminal justice system fairer for all New Yorkers," Manhattan District Attorney Cyrus Vance said in a statement last year.

Transit activists were conducting a day of action Monday, swiping in riders at subway stations across the boroughs.

“We have too frequent fare hikes these days,” said Albert St. Jean, 33, who helped riders at the Nostrand Avenue A/C stop Monday. “Every few months, it seems like it’s going up. It causes more people to jump the turnstile to try fare beating — and that criminalizes more of us.”

In addition to the presence at the Nostrand stop, the #SwipeItForward campaign placed more than a dozen transit advocates at the 4/5 station on East 125th Street and at the 74th Street 7-train stop in Jackson Heights.

The group plans to return to the neighborhoods during Monday evening’s rush hour.

“There are not really many alternatives,” St. Jean said. “They’re taking a necessity and using it against us. I think it’s bogus.”

The MTA has maintained these price hikes are necessary because of increased ridership and operational costs.