Irina....in due respect...i do not think that CC companies have this rule. An owner of any business can dictate the way they can use it. I do believe that they are not allowed to charge EXTRA for using a credit card.....but can discount anything they want. My wife's business accepts credit cards...but does discount frequently for cash. Also...down here in Florida....millions of restaurants offer a ''CASH ONLY" menu ...especially on their ''early birds''. Some will take a credit card, and it is clearly stated an upcharge for X Amount for using credit cards.