Officials from New York State say the state is missing at least $2.4 million in uncollected tolls.

Recently, the amount of unpaid tolls has risen since the expansion of cashless tolling in New York and officials believe unpaid tolls will likely increase in New York.

Even when uncollected tolls can be billed, law firms hired to collect outstanding tolls and fees have not been effective, an audit released by State Comptroller Thomas P. DiNapoli found.

"More needs to be done to ensure that those using our bridges and tunnels are paying the required tolls and that the TBTA is collecting the money it is owed, especially by the worst offenders, who persistently refuse to pay," DiNapoli said in a press release. "This audit identifies several ways to improve the collection of unpaid tolls, which is needed to help maintain and repair New York City's bridges, tunnels and transit system."

The state categorizes some unpaid tolls as "unbillable" because either the license plates captured on camera cannot be traced or are not legible.

The audit, which covered a period from January 1, 2013 to August 20, 2017, found that TBTA did not maximize toll collection for a variety of reasons, including license plate images that could not be processed and an inability to obtain addresses for some out-of-state drivers, resulting in potential lost revenue of $2.4 million.

The lost revenue calculation is a conservative estimate based on the assumption that all unbilled tolls are cars, officials say.  The toll for a five-axle tractor-trailer is almost five and a half times that of a car, according to the State Comptroller's office.

DiNapoli's audit also found that the three law firms hired by TBTA were not effective in collecting from toll violators.

If these issues are corrected, it appears it will only worsen in the future, because last month Gov. Andrew Cuomo announced more toll booths in the state will become cashless tolls.