The more mobile the members, the more material foreign transaction fees become, not just to the bottom line but to members' perceived value of their cards.

The Vienna, Va.-based Navy Federal Credit Union, for example, has a heavy concentration of military members who are constantly deployed or stationed overseas. In January, the credit union, which has 2.4 million cardholders, according to Vice President of Credit Cards Randy Hopper, eliminated the last of its foreign transaction fees across the board.

Hopper said the $73 billion credit union, which has six million members, started eliminating foreign exchange fees on two of its cards about three years ago.

"That benefit was something that we knew they would value," Hopper said.

Member characteristics were also a big factor for the Alexandria, Va.-based Pentagon Federal Credit Union, which has $19.5 billion in assets and 1.4 million members. It, too, does not charge foreign transaction fees, according to spokesperson T.V. Johnson.

"We were actually one of the first credit unions to waive these fees, and the decision came out of providing the best value to our core membership, which includes military personnel, defense contractors and their families," he said. "The fact that we have so many members living, working and posted overseas had a huge impact on this decision."

2. Marketing prowess

In order to maximize the return, credit unions have to find ways to make members aware of their cards' new value proposition. For example, Navy Federal tied its fee waiver announcement to its rollout of EMV cards.

"There was an opportunity to also say, 'You now have the security of chip and the peace of mind that you won't incur any [foreign transaction] fees when you're traveling overseas,'" Hopper explained.

Rolling the announcement out as part of a regularly scheduled fee refresh is another option, he said.

"What we found is that when we just did it on a few products, it was certainly effective in attracting certain types of members for that product. But we've seen a much bigger response in the last two months since we started waiving it across the board," Hopper said.

Credit unions thinking about eliminating foreign transaction fees should remember to change it everywhere.

"You have to make sure that you have it as a message across all channels," Hopper cautioned. "So if they call in, if they visit a branch, if they go online, you want to make sure that the message is consistent. We have to figure out the best way to tell everyone who already has a card with us that their card just got more valuable."

3. A business case

Ultimately, the decision has to make financial sense. Hopper, for instance, said waiving foreign transaction fees at Navy Federal has produced measurable returns.

"We did see feedback from members in the form of higher account openings," he said. "We saw higher compound annual growth rates in both of those products above and beyond what we have been seeing from a growth perspective."

Ray Crouse, president/CEO of the Pasadena, Calif.-based Parsons Federal Credit Union, is understandably skeptical about how those results would apply to smaller credit unions like his. Parsons, which has $222 million in revenue and about 6,600 members, caters to engineering firms with employees all over the globe who do a lot of traveling.

"To me, if that card is in their hand, I'm not sure it's going to make them use it more. It's already in hand," he said.

Parsons' credit cards carry a 1% foreign transaction fee – well below the industry average of 3% found in the CreditCards.com survey. It makes just about $6,000 a year on foreign transaction fees, Crouse said, and those fees cover fraud risk, additional support for members overseas and work necessary to help faraway members with lost or inoperative cards.

And like many CEOs of small credit unions, Crouse has to keep a sharp eye on tight margins that make it difficult to turn down revenue.

"If we tripled it, it'd be $18,000 a year," he said. "For a small credit union, with the interest margins the way they are, every little bit counts. Now, I would love to have an extra $1,000 a month if we just took it to 2%, but that's just not our business strategy. It's a give-back to the members, and we do realize they recognize it."

Hopper acknowledged that turning off fees comes at a risk.

"Once we eliminate a fee, it's gone," he said.