Yes a bank can ask for a higher down payment. This has happened to a couple of my clients. When the bank did a final check the peoples income to debt ratio was just a little bit high and to off set this the bank had the buyers put up between $200 and $500 more for a down payment to get this back in line. These banks right now are under a lot of scrutiny and little things like this have to be done to make sure the loans meet all the guide lines. I hope this is helpful to you.