Fort Lauderdale, Fla. ? A warning to all those credit cardholders who pay just the minimum amount due each statement: Your monthly bill is probably going to increase, if it hasn’t already.

Several major card issuers – including Citibank, MBNA and Bank of America – have raised or in the coming months will raise the minimum payment required of their cardholders.

The reason: In 2003, the federal Office of the Comptroller of the Currency, part of the Treasury Department, issued guidance requiring banks to have their monthly minimum payment cover interest, any fees and paying down principal. But some institutions are just now implementing the changes.

For instance, Citi Cards will boost their minimum payment requirements this year so that the amount covers finance charges and 1 percent of a card’s balance, said Janis Tarter, a spokeswoman for Citigroup.

Bank of America changed its minimum payment requirements last year and now charges cardholders at least $10, plus fees and interest, spokeswoman Betty Riess said.

MBNA will apply its changes later this year.

Many banks require minimum payments that work out to be about 2 percent of a card’s balance. When the changes take effect, the minimum requirement could be as much as 4 percent, experts say.

For someone with a $2,000 balance on a card, that means the difference between a $40 minimum payment and an $80 minimum payment.

Because a credit card is essentially a loan between the cardholder and the issuer, the loan eventually has to be paid back. But officials found some people had a hard time paying down those balances if they were just paying the minimum.

In some cases, the balances increased even after a payment was made, because the minimum payments weren’t enough to cover all the interest that accrued on the account, said Kevin Mukri, a spokesman for the Office of the Comptroller of the Currency.

“We require banks to not carry bad loans on their books,” Mukri said. “Sometimes these (credit card) balances would increase, and there’s no way the consumer could pay it back.”