WASHINGTON -- The Government Accountability Office has been ordered to study the use of credit by consumers, and in particular the effect interchange fees have on consumers and merchants.

Many people may not be aware of these fees, but for lenders, merchants and consumer advocates, the fees are the next controversial credit-related issue Congress may take up.

An interchange fee is paid by a merchant's bank to a customer's bank or credit union when the business accepts purchases by credit or debit cards. Typically the fees are between 1 percent and 2 percent of the total cost of a purchase's value. So, for example, if a consumer purchases $100 of merchandise or services the interchange fee paid by the merchant could be $2.

This may not seem like a lot of money, but multiply that by the millions of people making electronic purchases and it's not chump change. Moreover, everybody pays, whether you use plastic or not, according to consumer advocates and retailers. The interchange fees result in higher prices for everyone, including those paying with cash.

The Credit Card Accountability, Responsibility and Disclosure Act that President Obama recently signed into law includes a provision to investigate the fees businesses pay in order to allow their customers to use credit. The idea is to provide more transparency to consumers.

Demanding that credit card companies give more information about interchange fees would put them on par with food producers who are required to provide nutritional information on packaging. The nutritional details are meant to help people make healthier choices. And yet Americans are fatter than ever.

The same can be said about our appetite for credit.

Yes, with more information some have used credit better than others and haven't been trapped by fatty interest rates and fees. Still, this country's collective unhealthy devotion to credit has helped push us into this recession, increasing the cost to all of us.

As profit margins narrow, coalitions of business owners have been mounting campaigns to reduce interchange fees. Several members of Congress have introduced legislation intended to help businesses better negotiate the fees.

The moaning merchants claim they are fighting for their customers. I'm not so sure. Isn't it more likely that if their margins are tightening they'll just pocket the amount saved on lower fees?

Bankers argue that the fees are necessary as part of the costs to run the credit system, including providing reward programs. They say consumers will suffer if they don't have the convenience of paying with plastic.

Both merchants and bankers are serving their own interests in encouraging or opposing any legislation providing more transparency on interchange fees.

When merchants accept credit cards, people spend more than if they pay for their purchases with cash (a fact backed up by a number of academic studies). Continued...