Consumer lending experts say banks are starting to boost their credit card rates and fees in response to tightening by the Federal Reserve Board and heated competition for deposits.

Credit card industry officials estimate that 8 percent of all credit cards have variable interest rates that change monthly, quarterly or semiannually. Those rates have been rising along with other bank lending rates as the Federal Reserve Board boosts the discount rate it charges on loans to banks. Banks also are under pressure to boost rates to support higher payouts on certificates of deposit and money-market funds.Therefore, credit counselors say, it is time to examine all the inserts that come with your credit card bills. Some of them might not be trying to sell you products but instead are warning of increased fees, late charges or interest rates.

"I think as bank-funding rates increase and the spread (between cost of money and profit) narrows, you are going to see raised rates, whether they are raised across the board or whether there is price segmentation," said Peter Williamson, president of Credit Partners Inc., a New York consumer credit consulting company.

"The trend is up," said Spencer Neilson, who publishes the Neilson Report, which watches the credit card industry. "They are all not going to go up immediately, but they will go up."

Neilson said the average credit card rate now is 18.7 percent, but he expects it to go to 19.5 percent in a year. Tracking the increases is difficult, he said, because more than 600 banks issue cards.

As of March 1, Chase Manhattan Bank raised its rate for new customers from 17.5 percent to 19.8 percent. Bank industry sources say that the big New York bank is imposing the higher rate on some existing customers who have shown a pattern of late payments. Chase would not confirm that.

"Costs are higher; market rates have risen and so have administrative costs," Chase spokesman Fraser Seitel said. "We are trying a basket of rates to see what is right. We have some . . . of 17.5, some 19.8, some variable rates."

A spokesman for Citibank, the nation's largest credit card issuer, said that the bank had not changed rates recently, but he said he would not discuss the bank's future plans.

There are other ways for banks to make more money from credit cards. Increasing the annual card fee is one. Another is to shorten or eliminate the grace period on purchases, which means interest charges begin sooner after a purchase. They can also charge fees for customers who exceed their credit lines.

Nationally, banks are raising both rates and fees. Chevy Chase Savings Bank in Maryland, which had issued a low-rate card, raised its rates last month from 14.9 percent to 15.9 percent. First National Bank of Chicago chose not to raise its rate, but it cut the period before a late charge is imposed from 30 days to 10 days after the payment is due and then added the fee to the average daily loan balance, which increases the interest payments.

Williamson of Credit Partners suggested that an even higher charge could come into play for "convenience" customers, who use the cards to make purchases that are paid off almost immediately and who don't run constant revolving balances. Those customers typically generate less income than revolving-charge customers.