Payment networks Visa and MasterCard will impose the highest fees for even the smallest debit transaction for cards issued by JP Morgan Chase and Citigroup as allowed by a U.S. law that put caps on such fees.

The raise will triple the current charge on retailers for below $15 transactions starting Oct. 1, the effectivity of the new Federal Reserve cap rules for card fees as required under the Dodd Frank Act passed in June 2010.

Currently, the swipe charge of 1.55 percent of the purchase price plus 4 cents for under $15 purchases translates to 7 cents fee for a $2 cup of coffee. With the raise, retailers will pay 21 cents plus 5 basis points of the total and a conditional 1 cent for fraud-prevention.

The raise is expected to raise a howl from retailers, who will bear the brunt of the high swipe fees. About 20 percent of all debit-card purchases in the U.S. are small-ticket, Bloomberg cited TowerGroup senior research director Brian Riley as saying.

"The mom-and-pop coffee shop that processes lots of $3 transactions is really going to get hurt by this," said Brian Dodge, a spokesman for the Retail Industry Leaders Association (RILA), according to Bloomberg.

The RILA is a trade group representing the biggest U.S. merchants, including Wal-Mart Stores Inc., Target Corp. and Home Depot Inc.
However, the new fees do not cover cards issued by banks and credit unions with less than $10 billion in assets.