Going on standby?

Starting next year, merchants can charge customers a fee when they pay for goods or services with a credit card. While the levy may not amount to much, it could concern a particular group of card users, according to one financial adviser.

Points-accumulating frequent fliers — who often make purchases with airline mileage credit cards to build up points for free travel or goods and services — will have to rethink their strategy, said Richard J. Durso, a financial planner at RTD Financial Advisors Inc.

“If there is a fee and it works out to be significant, they will have to compare the benefit of the miles versus the additional cost of doing the transaction,” Mr. Durso said. “They may be able to negotiate a lower fee.”

According to many travel experts, one frequent-flier mile is worth an average of 1.2 cents.

Mr. Durso set out eight financial commandments for good money management on the Financial Planning Association’s consumer website this month. The second commandment is to pay credit card balances monthly. If cardholders adhere to that rule, he said, it probably won’t make much difference if they sometimes have to pay a small fee for the convenience of using the card.

“It is still better to use a credit card than a debit card because of the greater consumer protections,” Mr. Durso said. “I don’t know if [the surcharge] will be enough to warrant not using it.”

New rules that let merchants charge customers more to pay with a credit card are part of a $6.6 billion settlement agreed to by Visa, MasterCard and several credit card issuers to settle a 2005 lawsuit filed by a group of U.S. retailers. The surcharge rule is likely to go into effect early next year, according to Visa Inc.