EDIT: I added special benefits to my mortgage calculator.
See
http://applevalleyblogs.blogspot.com/2016/09/simlish-credit-worthiness.html
for additional details.
Military Service
If a sim is a military sim, or veteran, then they get an extra 10x their total salary added to the loan amount (so if they are making $770 in the service, the get an extra $7700 added to the loan, which rounded up to nearest $1000 is $8000). I might add extra benefits as I encounter them