Credit cards have long been a very good deal for people who pay their bills on time and in full.

Even as card companies imposed punitive fees and penalties on those late with their payments, the best customers racked up cash-back rewards, frequent-flier miles and other perks in recent years.

Now Congress is moving to limit the penalties on riskier borrowers, who have become a prime source of billions of dollars in fee revenue for the industry. And to make up for lost income, the card companies are going after those people with sterling credit.