These rules, written long before mobile banking started, don't cover deposits using a smartphone.
So, why the longer hold times for mobile deposits? The banks say they do it to prevent fraud.
"In order to ensure that the check is valid, we allow additional time for further verification and processing of these types of transactions," American Express explained in a statement.
GoBank told CNBC it approves the vast majority of checks for established customers either instantly or within a few hours. It will hold checks that cannot be immediately verified longer in order to make sure it's legitimate, it said.
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Use your banks' mobile app to deposit checks and you'd better find out what the policy is for making those funds available—and then plan accordingly, so you don't start bouncing checks. Direct deposit for your paycheck or an in-person transaction will probably be a lot faster.
Consumer Reports would like to see Congress update the rules to close the mobile deposit loophole.
"The times are changing and the banks should know pretty quickly whether that's a bad check or not. They don't need 10 days to figure that out," Blyskal said.
—By CNBC contributor Herb Weisbaum. Follow him on Facebook and Twitter @TheConsumerman or visit The ConsumerMan website.