Subway riders have given the MTA almost $70,000 in counterfeit money over the past three years, handing over more than 3,300 bogus bills to station agents and MetroCard vending machines, according to data.

So far this year, straphangers have bought at least $22,559 worth of MetroCards using 972 bills, according to the MTA. Most counterfeits are taken in by station agents, who risk having the money taken out of their paychecks if they don't catch the funny money, transit officials said.

In 2014, the MTA got $23,279 in fake money, from 1,118 counterfeit bills. The year before, it took in $24,154 in bogus cash, in a total of 1,218 bills.

Currently, agents are required to use a special pen to check bills to see if they are counterfeit.TWU Local 100 officials said that agents are also expected to check bills against a list of serial numbers to make sure they are legitimate, but that it is a time-consuming process that is not realistic in busy stations like Times Square-42nd Street.

"Who is going to check the list in Times Square?" said Paul Flores, a section vice chairman for station agents at Transport Workers Union Local 100.

To fight fake bills and help out station agents, the MTA and union launched a pilot program together in 2013 that uses counterfeit-detecting technology.

The Fraud Fighter CT-550 is a machine that checks whether a bill is fake and spits it out. Station agents are using two of the machines at subway stations in the Queens and the Bronx.

"The machine that has been in the pilot is working beautifully," Flores said. "We want a machine in every booth."

The union says the disciplinary process around counterfeit bills is costlier to the MTA than the fake bills are. There are about 900 hearings a year, officials said, which can cost the MTA several hundred dollars an hour.

"They are wasting money," Flores added. "It's outdated. The counterfeiters have found a way to combat the pen."

A station agent at the Jamaica Center-Parsons/Archer station said the Fraud Fighter CT-550 they recently received is a "wonderful idea if it worked." However, she said they still needed to learn how to use it. The station can be a target of fraudsters because of how close it is to the airport.

The MTA said it will make a decision whether it will expand the pilot once it assesses how successful the machines have been.

"We're in the process of evaluating the pilot," said spokesman Kevin Ortiz. "This represents a minuscule amount of money, based on the yearly amount of money we handle."

The MTA's station agents and vending machines handle about $1 billion in cash a year from riders.