One of our counselors asked: "I have a client who is looking for ways to cut her credit card processing expenses and is considering charging her credit card customers a $1 fee per transaction. I looked into this a couple years back when another client had a similar question and now can’t seem to find that information again. But, I recall that I had discovered that charging such a fee is against the merchant’s agreement with the credit card companies." This led to a vigorous online discussion. As it turned out, I did address this in the second half of this post , but that was five years ago. Has anything changed? I went to the sources, and included some related issues. MasterCard Rules (PDF) 5.8 Card Acceptance Requirements (start on p 122) 5.8.1 Honor All Cards A Merchant must honor all valid Cards without discrimination when properly presented for payment. A Merchant must maintain a policy that does not discriminate among customers seeking to make purchases wit...