"Fly to London for $198!" The advertisement seemed too good to be true.

And it was -- once you factor in all the hidden taxes and fees.

For the last month, British Airways held a big off-season sale on travel to and from Europe, offering flights to London for as low as $198 roundtrip. The deal was so good, travelers were doing double takes looking for the catch. And of course, as with most sale fares, there were a number of catches -- taking advantage of the $198 roundtrip wasn't easy.

In order to receive the absolute lowest fares, travelers had to depart and arrive on Mondays, Tuesdays or Wednesdays. Roundtrips with arrivals and departures on Thursdays and Fridays cost between $258 and $298. Some roundtrips on Saturdays and Sundays -- two of the more popular arrival and departure days -- cost as much as $1,400.

And even if you were able to fly early in the week, those rock-bottom roundtrips rapidly sold out, especially in October and November, putting the starting price of the cheapest roundtrip at $258, instead of the advertised $198. And these are just the advertised list prices of fares -- none include the blizzard of taxes and fees shoveled into the price you actually pay, which significantly jack up the price of an international ticket.

When all was said and done, that $198 roundtrip actually cost more than $300.

"It's like your phone bill, how the phone is $12 a month, but it ends up costing three times that after they add in all the little fees," said Brian Barth, CEO of SideStep, an online travel search engine.

A Taxing Equation

Even professional travel agents have trouble figuring out taxes and fees, with airports and governments all demanding a tiny sliver of the travel pie. Also, carriers charge all kinds of different rates and fees for fuel, security and even little extras like $20 for paper tickets or $100 for an oversized bag.

For example, British Airways charges a security fee of $4 per segment, per person, which means you could be charged as much as $16 for a roundtrip flight with one stop both ways. Unlike U.S. carriers, the international carriers have successfully implemented a $10 fuel surcharge per person, per segment, on all international flights. Again, this means you could pay as much as $40 per person for a roundtrip flight with one stop both ways.

Mind you, these are just the fees -- as Barth notes, "airline fees and taxes are even more complex because of all the governments and different levels of government." Local, regional and federal governments add -- or don't add -- certain fees to certain tickets for all manner of reasons. Some taxes are charged to all passengers in the name of airport maintenance, while other taxes are charged more selectively.

The U.S. government charges at least $40 in tax to an international ticket, adding roughly $18 for departing and arriving with a $15 tax for immigration and customs. This is only half the equation, however. If you're flying overseas, the country you land in will charge you as well. The U.K. adds as much as $75 to tickets -- a rate that varies from country to country and fluctuates with the currency exchange rate.

As the chart shows, fees and taxes can add up in a hurry. But with so many moving parts, airlines like Kuwait Air or British Airways aren't being entirely disingenuous when it doesn't add tax to sale fares. It can be too cumbersome to explain in even the finest of fine print.

"It's really easy to cast this as a bait and switch, but it's not evil by design," Berth said. "Depending on the routing, taxes can be different. Like you could end up paying less for a nonstop because you don't stop at some other foreign airport that has to add in fees and taxes, too."

How to Avoid Sticker Shock

The easiest way to avoid sticker shock is to assume that the actual price of an international ticket will usually be $100 higher than the sale fare advertised in the newspaper.
$240 Going on $340
Kuwait Airways has a $240 roundtrip flight between New York and London, but taxes and fees add 40% to the price. Here's a look at how the fees and taxes add up.
Item Cost
List price of the roundtrip fare $240
U.S. September 11th security fee $2.50
U.S. passenger facility charge $3
U.S. international departure tax $13.70
U.S. international arrival tax $13.70
U.K. passenger service charge $18.51*
U.K. air passengers duty $35.59*
U.S. customers fee $5
U.S. immigration fee $7
U.S.D.A. APHIS fee $3.10
TOTAL $342.10
Source: SideStep (* 1 British Pound = $1.78)

Using the Internet will make it much easier for you to comparison shop based on final price, since most of the online third-party search engines -- like SideStep -- list their fares with taxes and fees already included. On AirFrance's Web site, the carrier boasts of a $428 roundtrip between San Francisco and Amsterdam, but a savvy traveler checking Orbitz.com will not only see that that one-stop flight really costs $633, they'll see that Northwest Airlines has a nonstop that's $64 cheaper.

One of the best ways to dodge sticker shock, especially when booking last-minute travel, is to book a package. Not only will those pesky taxes and fees be folded in, but you'll have hotel and airfare -- and a rental car, if you want one -- for one set price that can offer a nice savings over buying flights, hotels and cars individually. Tour operators often buy up airline seats and hotel rooms that would otherwise go unsold and offer big discounts, thinking that some money is still better than no money.

Site59.com, which just unveiled a clever "last-minute" search feature, is a particularly good site for package deals. Forget the promise of a $198 roundtrip that doesn't deliver. If you wanted to go to London this weekend, the site has a hotel and air package starting at $414 -- and that includes all the taxes and trimmings.

If you liked this article you might like

US Airways Circles as Pilots Bicker

US Airways Circles as Pilots Bicker

Departure of Delta's Song Unit Boss Stirs Questions

Departure of Delta's Song Unit Boss Stirs Questions

Boeing Boosts Jet Deliveries

Boeing Boosts Jet Deliveries

CEO Gilmartin Will Survive Recall

CEO Gilmartin Will Survive Recall