Metro will no longer allow riders to accumulate negative balances on their SmarTrip cards, beginning Jan. 8. (Marlon Correa – The Washington Post)

Metro riders in the red — and approaching it — will want to load up their SmarTrip cards ahead of Monday’s commute.

Starting Monday, riders will no longer be permitted to enter or exit the system with a negative SmarTrip balance. Riders could previously take one trip resulting in a negative balance up to $1.50, but Metro warns that beginning Monday, the faregates won’t open for those who don’t have enough on their cards to cover their trip.

That includes rail riders who don’t have the $2.25 peak, and $1.75 off-peak minimum fares loaded to their SmarTrip cards.

Meanwhile, customers who meet the minimum fare but whose trips costs exceed their balance will be directed to exit fare machines, which only accept cash and coins. The agency said, however, that station managers will be at the ready to walk customers around to credit and debit card-accessible machines if needed.

Bus riders who don’t have the $2 fare loaded on their cards will be met with a buzz at the farebox, Metro said. And those with passes pre-loaded to their SmarTrip cards need to have a positive stored value to ride the system, Metro said — even if their trips are covered by their pass products.

It’s the first day of a policy that the cash-strapped agency says underscores how “every dollar counts.” The agency said negative balances have added up to $25 million in losses over the past 17 years.

But some riders and advocacy groups are pushing back. Monday afternoon, a union-backed group known as the Save Our System Coalition plans to protest the move, holding a 4 p.m. rally and SmarTrip giveaway at the Anacostia Metro station, in opposition to what it calls the “negative impact” of the move and heightened fare enforcement policies that “disproportionately target low-income communities,” specifically black residents, according to the group.

Metro General Manager Paul J. Wiedefeld has previously defended the agency’s heightened focus on fare evasion, while noting individuals’ concerns about unfair targeting. Metro Transit Police Chief  Ron Pavlik, Jr. has said the agency doesn’t keep demographic data on fare evasion citations.

“It’s a fairness issue, across the entire community,” Wiedefeld said when the question was raised previously. “You have people in those same communities that they’re concerned about being targeted, who are paying their fares. And I think it’s right that everybody pay their fare.”

Despite the aggressive push to enforce its fares, Metro said the negative balance policy is distinct from the police crackdown on fare evasion.

The agency noted in a news release that fewer than 1 percent of passengers had a negative balance on their SmarTrip cards last week.

“We do not expect any significant issues from this change,” Metro spokesman Dan Stessel said.