Citigroup Inc. said it has raised its rates on some credit cards this year as it reviewed its risk exposure and its needs to counter rising business costs.

Citi has boosted rates on up to 15 million U.S. credit-card accounts cards it co-brands with retailers such as Sears Holdings Corp. (SHLD 78.68, +2.41, +3.16%) according to a report earlier Wednesday in the Financial Times newspaper.

Many card issuers are tinkering with rates now, to get in under the wire, leaving consumers struggling with how to respond properly.

The movement to reform credit card practices is gaining speed as the White House and Congress target punishing fee practices they say are contributing to a growing number of Americans’ financial distress.

Banks say that higher funding costs, along with surging loan delinquencies and defaults, have forced them to reassess credit card risk.

When banks change credit card rates, consumers are often given the option of opting out, meaning they can pay off the debt at the same interest rate as long as they don’t make any new purchases. But if the bank raises rates because of a late payment, the consumer generally doesn’t have the option of refusing the higher rate.