Q. My family and I travel frequently between New York and Zurich, Switzerland and have noticed that fares from Zurich to New York are much lower than those from New York to Zurich. Why is this and is there a way to “game” the system? Can I buy a round-trip fare from Switzerland to the U.S. while I’m physically located in the U.S.?

A. We’ve noticed the discrepancy as well, on many routes between the U.S. and international destinations. Besides the all the taxes and innumerable fees involved in international travel, which vary by country and itinerary, airlines charge what they think the market will bear in each country. Currency exchange rates may also play a role. If you’re starting your journey in Europe and flying round-trip to the U.S., then there’s no reason why you can’t buy a fare in the local currency at the local price. But if you’re physically in the U.S. and don’t have a European-based credit card, then this may not be possible.