Evan Schuman's StorefrontBacktalk

The legal fight over the interchange settlement is still going on, but the deal’s first effects will still show up this month. Beginning January 27, retailers will have the option of tacking on a surcharge for payment-card transactions. No, the class-action settlement still hasn’t gotten final approval, but the terms take effect 60 days after U.S. District Court Judge John Gleeson gave it preliminary approval in November 2012. (It’ll be rolled back if the settlement is ultimately rejected.)

Let’s be clear: Add-on swipe fees are still illegal in New York, California, Florida, Texas, Connecticut, Massachusetts, Maine, Colorado, Oklahoma and Kansas, which together represent about 40 percent of U.S. retail sales. And many big chains have already said they think a surcharge will encourage customers to walk away at the POS, so they’re not doing it. That means retailers who do implement a surcharge will make a nice lab test for the rest of retail to see how much customers are willing to accept. The answer is probably “not much”—U.S. customers love their plastic—but we may yet be surprised. There was a time when banks and airlines thought they couldn’t get away with nickel-and-diming their customers to death, either.