Starting Sunday, merchants who honor two major credit cards are allowed to add a service charge to transactions.
An antitrust suit brought against Visa and MasterCard resulted in a settlement.
As part of that settlement, Visa and MasterCard did away with a rule that had prohibited the surcharge.
The charge would allow merchants to recover the cost of processing a credit card transaction. The fee is capped at 4 percent.
It is unlikely shoppers will see the service charge added at many of the stores where they shop.
Major retailers like Wal-Mart, Target and Home Depot have said they have no plans to add the charge.
Additionally, ten states have laws that ban credit card surcharges.
Visa and MasterCard rules say a retailer must handle credit cards the same way in all states where it operates. So if a retailer has a store in a state that bans the surcharge, it cannot add it anywhere else.
Also, the settlement says a retailer who adds a surcharge to Visa and MasterCard purchases must do the same with other cards. American Express prohibits surcharges. So, any merchant who accepts American Express in addition to Visa and MasterCard cannot add surcharges on any card.
Some consumer advocates point out that smaller retailers will be less likely to add the surcharge because it would complicate transactions.
Others say many retailers already factor in the cost of credit card processing when they set their prices.
The change allowing surcharges does not include debit card transactions.