Be careful with your debit card this holiday season. Of course, that holds for the rest of the year. Still, it’s all too easy during the hectic holiday season to overdraw your account online and at the mall.  You could end up paying steep fees.

Pew has a nice interactive graphic on how banks can manipulate your debit card transactions to boost overdraft charges. Toggle between the two bank statements and you can see how a bank can increase — or minimize — overcharge fees by manipulating the order of debit card transactions. In their example, the bank managed to boost the fee four times. Ouch!

Pew notes that a number of large banks, such as Wells Fargo, Citi, Chase and HSBC have announced that they’ve renounced the practice illustrated in their graphic. That’s good, although it shouldn’t have been done in the first place and there are plenty of other banks in the country that haven’t taken the pledge.

Pew has a number of worthwhile projects on consumer finances, including making credit cards, small loans, and banking relationships fairer to customers. It’s worth spending some time on their website.