Merchants can set a minimum amount for credit card transactions, but there are some limitations and regulations that they must follow.

According to 2010 ruling under Dodd-Frank law, a business is allowed to to set a credit minimum as long as such minimum dollar value does not exceed $10.00; and does not differentiate between issuers or between payment card networks, meaning that four payment processor networks: Visa, Mastercard, American Express and Discover need to have the same requirements. 

Adding surcharges is legal. The surcharge amount cannot exceed the cost of processing the credit card transaction, typically up to 4%. Merchants must also meet specific disclosure and notification requirements, both at the point of sale and on receipts. Not all states allow surcharging, so merchants should check the regulations in their specific location.

Merchants cannot set a minimum amount for debit card purchases. The primary reason for not allowing minimum transaction amounts on debit cards is to ensure that consumers have access to their funds without being subject to arbitrary restrictions. Imposing a minimum transaction amount could limit consumers’ ability to make small, convenient purchases using their debit cards.