NEW YORK (sbup) – Two studies out this week show that U.S. consumers are increasingly reliant on debit cards, even though tougher regulations may have led to higher fees, and even though more bank checking account overdrafts may be imminent.

The first study, from Lake Forest, Ill.-based Moebs Services, reports that debit card transactions now account for 43% of all retail transaction, up substantially from 19% back in 2003.

That’s no coincidence, Moebs says. In 2003, Congress passed the Check Clearing for the 21st Century Act (more informally known as “Check 21”). The act eliminated the traditional “float” on paper-based checks that, in many cases, reduced the number of overdraws on consumer checking accounts.

Moebs is able to peg a dollar figure on floats, noting that in 2003, floats averaged about $10 billion per day. But by last year, Check 21 had changed the checking account landscape, with only $400 million in paper check-based floats, a reduction of 96%, the company says.

That means Check 21 has pretty much closed the window on floats, leading to a huge uptick in debit card usage and a big increase in overdraft penalties.

"The lack of float and increased debit card usage has made the time between initiating payment and depositing payment almost non-existent," Moebs says. "With 87% of checking account users not reconciling their checking accounts, the probability that the average consumer will overdraw is immeasurably increased."

A second study, this one by Houston-based Discover Financial Services, says the PIN-based debit card market will rise by 15% this year and signature-based debit card use will grow by 8%.

Discover’s 2012 Debit Issuer Study notes that debit card transactions were way up last year despite tough regulations coming out of Washington, D.C.

“The latest Debit Issuer Study provides more evidence that growth in debit remains robust even in the face of significant regulatory headwinds,” notes Steve Sievert, an executive vice President of marketing and communications for Pulse, which conducted the study.

Consumers seem to have been hit indirectly by the Federal Reserve’s Regulation II mandate, which caps the amount of money debit card issuers can get on card transactions. The DFS/Pulse survey says 89% of debit card issuers say “regulatory pressure” is their biggest challenge now.

Those same issuers are losing money on card transaction “interchange” fees and looking to recoup those losses by eliminating debit card rewards programs – a big favorite of consumers – and adding more service fees to bank checking accounts.

Altogether, financial institutions report debit card revenue declines of 55% for signature transactions and 28% for PIN transactions, Pulse reports.

Still, consumers are using their debit cards.

Pulse reports the average debit card users spent $8,326 on their card last year, compared with $7,781 in 2010. Transactions at the low end of the spectrum have really picked up, with 30% of all transactions for purchases of less than $10.

That means, tougher regulations or not, consumers are turning increasingly to their debit cards to make purchases.

Banks and card carriers may make less money on each transaction, but they may be figuring out that what they lose in fee rates, they may be making back in volume.

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