The change is designed to help ensure that mobile banking app users aren't able to deposit a check online and then again at a brick-and-mortar bank. Getty Images By Lisa Gerstner, Contributing Editor October 3, 2018From Kiplinger's Personal Finance When you use your bank or credit union's mobile app to deposit checks, you may have to start adding more-detailed wording below your signature to ensure that your check will be accepted. The change is designed to address concerns that customers may deposit a check via mobile app with one bank and later deposit the original check at a second institution. In a rule issued this summer, the Federal Reserve said the first bank can avoid taking a loss if the customer writes "for mobile deposit only" or similar phrasing on the check. The Fed hopes the rule will minimize fraud and accidental double deposits.SEE ALSO: Best Internet Banks, 2018 If your bank is updating its preferred language for endorsements, it may notify you by e-mail or post an announcement on its website. Or check its app—instructions may pop up as you are making a deposit. If your endorsement doesn't match the bank's model, it may reject the deposit. But many banks will accept the check and later tell you how to write the endorsement, says Matt Kriegsfeld, of Mitek, a mobile-deposit software developer.