Published: Nov 22, 2010 11:12 PM EST
Updated: Nov 22, 2010 8:13 PM EST

COLLIER COUNTY, Fla. - Holiday shoppers may want to double-check their bank accounts before swiping a debit card this season.

A Naples teen recently learned an important financial lesson after using his bank-issued debit card to buy fuel at an area gas station.

Ryan Millman, 17, says he's had his debit card for about a year.  The high school Junior works part-time and watches his balance closely.  A few weeks ago, he says he bought $10 in gas at a station off Pine Ridge Road. 

But when Millman got home and checked his account, he learned he was overdrawn.  He says the gas station charged him more than $50.

"I was really surprised," Millman told WINK News.  "I wouldn't spend that much money.  I didn't spend that much money, so how was that possible?"

Experts say it's both possible and legal.  It's called a debit "hold."

Here's how it works:  Certain businesses -- like some gas stations, hotels or car rental companies -- don't know how much you're going to spend when you swipe your card for pre-approval of a transaction.  So they ask your bank to block out, or hold, a preset amount of money until the purchase clears.

In some cases, as in Millman's, the hold can be for more than the actual transaction.  Some gas stations may hold as much as $100.

"The reason a merchant would put a hold on your account is for their own protection," says Dr. Howard Finch of FGCU's Lutgert College of Business.  "They get burned on a regular basis by people with either insufficient funds or who run a tab higher than is expected."

Finch says the holds are only temporary, usually reverting back to what you actually paid within a day or two. 

"I think it's probably happening more often than any of us are aware," Finch says.  "But for most people, because they have sufficient funds in the account, it's never been an issue."

For those who don't have enough funds to cover the hold, it can be a big issue -- one that results in overdraft fees or the refusal of a purchase.

WINK News called several banks.  Each told us individual merchants determine the amount of a debit hold.  Some will only "ping" your account, charging $1 to make sure it's active.  That's what happened when WINK News bought fuel at several local gas stations.

If you want to avoid a debit hold entirely, there are several easy tips to follow:

* Pay using a standard Credit Card.

* If you're going to use a Debit Card, enter your P.I.N. number.  This allows the merchant to collect at the point of purchase.

* Set an "Artificial Zero" balance on your account.  Finch recommends never letting your account drop below $200.

"The idea of using an 'artificial zero' balance would likely move you into that scenario where you wouldn't realize you had a temporary hold on your account because you'd never be overdrawn," Finch said.

In situations that result in overdraft fees, banks encourage clients to speak with a local branch representative.  In some cases, banks may be willing to drop the fee if the overdraft was the result of an over-priced debit hold.  That's what Millman's bank did for him.

"I check my account even more actively now," Millman said.  "I check to see if retail or food stores will do the same thing."