cardkeysOn second thought, maybe you should leave home without it.

For years, I’ve been telling travelers to pay with plastic and so have my buddies in the vacation punditry business.

Credit cards protect you from unscrupulous travel agents and tour operators. They hold companies accountable for substandard cruises, flights and hotel rooms. Plus, you can rack up more frequent-flier miles than you’ll ever be able to spend.

But what if the very payment system everyone swears by was quietly helping itself to your money, a few bucks at a time, when you travel? What if companies were quietly tacking new fees onto your bill when you were away?

No need to imagine. Let me introduce you to two fast-growing credit card surcharges: the foreign transaction fee and the airline ticket convenience fee.

The foreign transaction fee charges a flat rate — usually 2 or 3 percent — of any purchase that takes place with a non-U.S. company, regardless of your location or currency. In other words, you can buy a trip right here in the U. S. of A., pay in greenbacks and still get smacked with a foreign transaction fee.

Priceless.

For example, I heard from a reader a few weeks ago who booked her honeymoon in Canada through a U.S. travel agency. She paid in American dollars, but when she returned from her vacation, she found a surprise $310 foreign transaction fee on her credit card bill. Turns out she’d paid a Canadian company through her agent, incurring the surcharge.

To her, the fee represented nothing less than a money grab. Her bank did nothing to earn it and didn’t even bother to warn her before she made the purchase.

Remarkably, this case was easily solved. The newlyweds contacted their bank, and it promptly refunded its share of the fee.

I’ve seen that happen more than a few times lately. Many banks and credit card companies are rolling over when confronted with questions about these surcharges, which suggests that they know the fees are both exorbitant and inexcusable.

They should really know better. A few years ago, angry customers filed a class-action lawsuit against Visa, MasterCard, their member banks and Diners Club, claiming that they’d conspired to set and conceal a 1 to 3 percent currency conversion fee. That fee applied only to transactions where dollars had to be converted. The case was settled.

I’m at a loss to explain why, after the passage of a credit card reform bill earlier this year and with the prospect of tighter government regulation looming, banks and credit card companies would make the same mistake again — unless, of course, they’ve made all the right campaign donations and are confident that they can get away with this.

Unsurprisingly, my friends in the airline business also see an opportunity here. Two discount air carriers, Spirit Airlines and Allegiant Air, now charge fees to customers who pay by credit or debit card. Spirit adds a $4.90 passenger usage fee for bookings not made in person at its airport locations. And Allegiant applies a $14 surcharge to tickets booked through its Web site but waives this “convenience” fee if you buy in person at one of its ticket offices. Both are de-facto credit card fees.

There’s more to come. Forrester Research analyst Henry Harteveldt believes the airline industry can’t wait to embrace convenience fees. He notes that the Computerized Airline Sales and Marketing Association, a trade group for airline marketing professionals, discussed the idea at a recent conference.

“There are three airlines that might take the lead on this,” he told me. One is United, which is asking some travel agents to handle ticket purchases through their own credit card merchant accounts. Harteveldt and others believe this could lead the agents or airlines to start charging convenience fees to cover their own account expenses. “The other is American, which is tightly focused on finances and cost reduction, and US Airways, which acts like Spirit in almost every way possible.”

Steering clear of this surcharge isn’t as easy as protesting a foreign transaction fee. The extras are disclosed as part of the ticket price, and when they aren’t, the U.S. Department of Transportation can punish the airline, as it did this fall when it hit Spirit with a record $375,000 fine. These fees have been rare in the travel industry until now, but the few times I’ve dealt with them, the company has stubbornly refused to remove them.

Airline convenience fees make about as much sense as foreign transaction fees, which is to say, none. Does it really cost $14 to process a ticket transaction on a credit card? Should that cost be broken out from the base fare and only presented at the last minute, when you’ve already made a booking decision?

Those aren’t rhetorical questions. But you already know the answers.

If these fees are allowed to take root, they’ll be impossible to exterminate. Something tells me that market forces alone won’t kill them, and neither will the lone protests of a consumer columnist.

I suspect only government regulation can prevent these card tricks from continuing.

(Photo: Fosforix/Flickr Creative Commons)