WASHINGTON - Check your holiday credit card bills closely.

Some card companies are raising interest rates on good customers - even if they pay down their balances, on time, every month.

The reason these companies cite is that the customer's credit rating has fallen elsewhere.

That was a rude surprise to Janet Hard, a stay-at-home mother of two teenage boys from Freeland, Mich.

Depending on her husband's salary as a steamfitter while she raised the children was financially difficult, Hard said, especially with college tuition coming up. To keep their finances in balance, Hard said she paid more than the minimum payment on her Discover card every month, plus an $8 Internet fee.

Or so she thought.

In February, Hard noticed that despite her payments, the balance was "barely moving." A phone call to Discover solved the mystery, but not the problem: The company had raised her interest rate from 18 percent to 24.24 percent after running a credit report. It showed her other card balances and available credit on inactive accounts put the family at a higher risk of defaulting on payments.

So $3,478.39 of her $5,618 in payments went to Discover for interest over the last two years, Hard told a congressional panel yesterday.

"My husband and I feel as though we have been robbed," Hard told the Senate Permanent Subcommittee on Investigations. "As we struggle to overcome this financially, we also are struggling to overcome it on an emotional level."

The panel's chairman, Sen. Carl Levin (D., Mich.), is sponsoring a measure that would restrict increases in a card's interest rate to certain instances - such as at the conclusion of a low, introductory rate period, for contracts that have variable rates, and when a cardholder violates the agreement with the issuer.

Major card companies such as Citigroup Inc. and JPMorgan Chase & Co. have said they will quit raising a customer's interest rate based solely on a credit report. Capital One said its long-standing policy was not to change customers' interest rates if their credit scores went down.

But congressional efforts to make all cards companies do it are running into opposition from the banking industry.

Not considering changes to a customer's credit rating "is like taking the batteries out of a smoke detector," said Roger C. Hochschild, president of Discover Financial Services L.L.C. "It's important criteria."

He and other industry executives told the Senate panel that cardholders are appropriately notified of any changes and given time to opt out and pay off the card at the old rate and to contact the credit bureaus whose reports may have spurred the rise in rates.