For residents and students alike, keeping a car in New Haven may get more expensive.

Although the city taxes every car parked in New Haven for more than 90 days, City Hall last Tuesday announced a more aggressive measure to solicit payment of the tax from residents who have registered their vehicles out of state. City tax assessor Bill O’Brien estimated that at least 2,500 car owners — including a number of Yale students and faculty — currently fail to meet this liability.

City spokeswoman Jessica Mayorga said the city expects the new initiative to sizeably increase annual tax revenue. A similar system implemented recently in Bridgeport helped to generate an additional $1 million dollars; O’Brien estimated that New Haven may recoup about $500,000 over the next six to eight months.

“Everyone is obliged to pay the tax, and this includes students who will be charged in accordance to the law,” Mayorga said, though she denied the current economic downturn spurred the crackdown. “This initiative is about making sure that everyone pays their fair share,” she added.

The amount of the tax varies considerably according to the model and condition of the car, Mayorga said.

Car owners suspected of tax evasion will be served a notice, subject to fines and interest. And beginning this month, vehicles on public property may also be towed. The city hired Municipal Tax Services, a private company, to track down vehicle owners suspected of tax evasion. Already in operation in neighboring Trumbull, Danbury, West Haven, Waterbury and Bridgeport, MTS will monitor and photograph cars which have interstate number plates but appear to belong to New Haven residents, and then match the vehicles to their owners via a government database.

As payment, MTS will receive a 30 percent share of the additional taxes collected.

Of the four students interviewed Tuesday, all were unaware of the new tax initiative and expressed frustration at the possibility of having to pay additional taxes. Although his car is already registered in Connecticut, Rob Goldman ’11 said the latest crackdown was a bad idea.

“That students may be made to pay car taxes in more than one state is totally unfair,” he said.

Although Rhetta Nadas ’12, whose car is registered in Massachusetts, agreed that the new tax is a form of double dipping, she said the new measure will not affect her decision to keep a car in New Haven.

“My parents are paying for the car, and it is convenient to be able to drive to the gym in winter,” she added.

In order to register a vehicle in New Haven, an application must be submitted to a Department of Motor Vehicles office. Those wishing to transfer their registration from another state have 60 days to submit their application once proof of Connecticut residency is established.