A few weeks ago, Stacie Everett bought a battery for her SUV. Because she didn’t turn in her old battery at NAPA, the store charged her a $10 fee. And it charged her 5 percent sales tax on that fee.

The $10 fee – called a battery deposit – is required by state law.

But the tax on that fee?

Depends on who you ask.

Maine tax officials say battery deposits are exempt from state sales tax and that stores should never charge it.

“It’s clearly excluded,” said Peter Beaulieu, director of the sales, fuel and special tax division of Maine Revenue Services.

But area auto-parts dealers say the state has told them they absolutely must charge the tax and forward the money to the state. They fear stiff fines if they don’t.

“We’re bound by law,” said Mark Chinnock, owner of the Mechanic Falls NAPA store where Everett bought her battery.

An informal Sun Journal survey Thursday found widespread confusion over the deposit and the tax. Caught in the middle: customers who paid the 50-cent battery tax.

“It’s the principle of the thing,” Everett said. “It all adds up.”

The $10 battery deposit was created by the state years ago to get people to return their used car batteries for recycling rather than dumping them in the trash. Like the 5-cent deposit on bottles and cans, customers pay the battery deposit when they buy a new one and get that money back when they return a used one. And as with bottle deposits, no sales tax is applied.

The problem is that some stores appear to be confusing that battery deposit with an auto parts “core charge,” which also involves getting money back for turning in old parts, but is taxable. Customers often find core charges on alternators and other parts that can be reconditioned and resold. Stores impose an extra charge – a core charge – on the new purchase and then will return or credit that charge when the customer brings in the old part. But unlike the battery deposit, the state requires sales tax be calculated on the price of the product and the core charge together.

So, for example, if a person buys a $90 alternator and the store charges a $10 core charge, the store must base the sales tax on that entire $100 because the state considers the core charge simply part of the selling price. If the customer gets the $10 back for bringing in a used part, the state views it as a kind of trade-in credit, same as cash.

As far as the state is concerned, officials said, the customer was charged $100 for the part, paid $100 for the part and should pay sales tax on that $100. The fact that the customer traded in a used part for $10 off doesn’t reduce the sales-tax requirement.

On Thursday the Sun Journal surveyed 10 auto-parts stores, including chain stores and independent shops. All referred to the untaxed $10 battery deposit as a “core charge,” even though it is not.

Of the 10, six said they required a $10 battery deposit and charged sales tax on it.

Two said they didn’t require a deposit.

Only two, including Advance Auto Parts in Lewiston, appeared to follow state rules, saying they charged the deposit but did not charge sales tax on it. Advance national spokeswoman Shelly Whitaker said the company programmed its cash register computer system based on state laws. Whatever was programmed is what they follow.

“It’s all automated,” she said.

Other stores said their systems were automated, too. Automated to add on the tax.

At NAPA in Mechanic Falls, Chinnock called the $10 battery fee a “core deposit” and said he had routinely checked with the state and with fellow auto-parts dealers to see if he should tax it. He said he is always told yes.

Customers question the tax once in a while. Everett did when she found it on her receipt a few weeks ago. Chinnock said he tells everyone the same thing.

“We tell them, ‘Nope, we don’t agree with it. It’s not right. Call your representative in Augusta and complain to them because we have before and we’ve gotten the same answer over the last 20 years,'” he said.

It was unclear how many stores may be charging the tax when they shouldn’t. Businesses forward their sales tax to the state but do not itemize which product was purchased to incur the sales tax.

At Maine Revenue Services, Beaulieu said he had received few questions about the battery deposit, though his department routinely gets calls about core charges.

If customers have been charged sales tax on the $10 battery deposit, Beaulieu said, they should ask the store for that 50 cents back.

Chinnock would just like to know whether he should charge that tax in the first place.

“If the law reads any other way than that, we need to know,” he said.