Credit card users were assured last week that the days of sudden interest rate hikes and confusing contracts will soon be over, thanks to a new law that tightens lending regulations. But because the law does not take effect until February, card holders should keep watch for unexpected tweaks to their account over the next few months, financial experts say.

Credit card companies are hustling to make changes to many accounts - increasing interest rates, lowering credit limits, or shutting quiet accounts altogether - as they grapple with an unstable credit market and prepare for new regulations from Washington. Though those changes often go unnoticed by the card holders, they can end up walloping a household budget.

"It seems the card companies are clamping down on everybody now, regardless of your credit history or credit rating," said Jill Boynton, principal of Cornerstone Financial Planning in Newington. "They're starting now, I think, because they're looking to stem their losses before they have to change the way they collect fees and charge interest."

The new law will restrict some fees credit card companies charge. It prohibits retroactive interest increases on existing balances unless the borrower is more than 60 days late on a payment. Credit card companies will have to give 45 days notice before raising interest rates. The law also requires more disclosure to borrowers about the terms of their accounts and requires that those explanations be written in plain English.

Taken as a whole, the reforms are the most sweeping changes to the credit card industry in decades. And they have led to speculation that card companies may take other steps to make up for the lost revenue - including charging annual fees on all cardholders, raising interest rates on introductory accounts or cutting back on reward programs.

Meanwhile, many card holders are already feeling the more immediate effects of the card companies' scramble to offset their losses. Just ask Lester Zaiontz.

Zaiontz, a 51-year-old fundraising consultant from Concord, said he's seen the interest rate on his HSBC credit card creep up over the past few months, to 28 percent. But he got another shock earlier this month when the company lowered his credit limit from $10,000 to $3,900. The reason: Zaiontz wasn't charging enough on his card.

"But why would I use their credit line when they had raised the interest so high?" Zaiontz said.

Zaiontz called HSBC to question the changes. A customer service rep agreed to increase his credit limit by another $1,000 and reduce his interest rate by a couple of percentage points. But Zaiontz is concerned that the overall reduction in his credit limit will hurt his credit rating. Zaiontz said he carries a balance of around $1,800 on the HSBC card, and he doesn't plan to charge any more on it until its paid off.

"HSBC tells me I'm a valued client, but if I'm so valued, why do they do things like this?" Zaiontz said. "Their answer was, 'We have to cover our risk.' But I think they're so far removed from their public that they forget what these things do to the little guy."

Such changes will likely continue for many credit card users until the new regulations take effect next year. And they can have a big impact. A cut in your credit limit, for instance, will reflect poorly on your credit rating, since it means you have less credit available to you while your overall debt remains the same. And that could result in a further increase in the interest rate lenders charge you.

"A lot of people don't realize the way credit scoring works, but 30 percent of your score is weighted by the amount of debt compared to the overall credit you have," said Sara Varella, communications director for Consumer Credit Counseling Service of New Hampshire.

Many small businesses got an especially painful credit shock last week when they learned that Advanta, a popular credit card for small companies, would no longer accept new charges. The stoppage, which Advanta blamed on a rise in uncollectible debt, went into effect yesterday.

Some proponents of reform are already calling for further restrictions on creditors, including capping interest rates - a change that credit card companies have vigorously resisted.

Bottom line, make sure you pay attention to any notices you receive from your credit card company in the next few months. And read all the small print, too.

"We have seen a lot of cases where consumers don't realize they've been notified by the bank, and all of a sudden there's a rate increase, and they've already thrown out the information that came in the mail," Varella said. "The truth is, the whole industry is trying to protect itself from the consequences of the new law, and they want to figure out how to increase their income and reduce their risk before the new changes take effect."