A Form DD 256 is a certificate of honorable discharge utilized by the U.S. Department of Defense and the different branches of military service. An honorable discharge occurs when a service person successfully completes a term of duty with one of the military branches. This document is used to prove whether or not a veteran was honorably discharged, & many lenders require this document if a veteran served in the National Guard or Reserve, along with their Point Statement/NGB-22, and their DD-214.