When you write your earnest money check you want to show the seller that you are serious about buying their house. If it is a $400,000 house you do not want to write a $500 check. It would be more appropriate to write a $5000 check. For a $200,000 house I would want you to write a $2,000 or $3,000 check. Sure you could write a bigger check for an earnest money deposit, but there is an potential issue when doing that.