Hi kmkoeser, Most credit card merchants prohibit charging customers fees or minimums for customers using credit cards. By doing so, you are violating your agreement with the credit card company. Read more about credit card rules in our blog: Little-Known - But Important - Credit Card Rules For Merchant.

Visa merchants are not permitted to charge consumers a fee when they use a Visa card. See http://usa.visa.com/personal/using_visa/no-surcharge.html.

I wasn't aware of this - i've seen many Visa merchants with 'minimum purchase' signs or adding a service charge for credit card transactions. A couple of travel websites do this as well.

We recently paid our sales tax online and saw we can pay our sales tax using a credit card for an extra fee. This is called a 'convenience fee' and is charged by the state. I guess you can charge an extra fee as long as this can be considered a 'convenience fee'. http://www.merchantcouncil.org/merchant-account/operation/convenience-fe... I suggest you read and fully understand the official Visa and MC guidelines before charging an extra fee to make sure you are following the rules.