It takes Sgt. Charles Denault barely two minutes to spot a dozen cars with out-of-state license plates parked in driveways and outside houses and apartments.

Driving his cruiser along this streets of coastal Kittery, Denault is on the lookout for vehicles registered in other states _ especially New Hampshire _ but owned by people who live in Maine.

"They're everywhere," Denault said as he points out car after car with New Hampshire plates. "It's like dandelions that keep popping up."

By professing to live in New Hampshire, Mainers can avoid paying a 5 percent sales tax when they buy a vehicle. They also don't have to buy car insurance, which is required in Maine but not in New Hampshire. And people who work in New Hampshire can also avoid paying Maine's income taxes if they claim a New Hampshire residence.

A side effect is that they may end up paying slightly more to register their car in New Hampshire _ a negligible worry for Mainers already skipping out on paying other taxes but potentially devastating to towns like Kittery, which hurt as tax collections and state aid to the town go down.

Police say some people simply aren't aware that they're required by law to have Maine plates after 30 days of becoming a resident. But all too often, said Kittery Police Chief Ed Strong, money is the motivator.

Strong said offenders use all sorts of tricks to get around the law: Some claim to live at a relative's New Hampshire home or use the address of a rental or seasonal property.

"We have found people that have dummy addresses in New Hampshire to register their vehicles," Strong said.

Nobody knows for sure how many excise tax evaders there are in Maine or how much money the state and local towns are losing because of them.

In Maine, it would cost $305 in excise taxes and fees to register a 3-year-old midsize car with a retail price of $20,000; the same vehicle would cost $313.20 to register in New Hampshire.

Kittery police typically write 150 to 200 summonses a year for excise tax evasion, although the pace has accelerated over the past year.

But other towns aren't so vigilant.

Maine Revenue Services issued a report last year that concluded excise tax enforcement is a low priority in most of Maine's border towns.

Still, at the request of the Legislature, the agency this summer appointed an agent to work with municipalities to help them identify scofflaws, said Errol Dearborn, who heads the enforcement division of Maine Revenue Services. The aim is to boost excise tax collections on the local level and sales tax collections for the state.

Everybody ends up paying to make up for the people who are scamming the government out of taxes, Dearborn said.