Jim has an annual income of $185,000. Jim is looking to buy a house with monthly property taxes of $140 and monthly homeowners insurance of $70. Jim has $178 in monthly student loan payments. Apple bank has a maximum front end DTI limit of 28% and a maximum back end DTI limit of 36%. Given both limits, what is the most they will allow Jim to spend on a monthly mortgage payment?

I got $4,106.67 for the Front End DTI Limit and $5,162 for the Back End DTI Limit, I wanted to know why is it that we choose the Front End Limit ($4,106.67) instead of the Back End Limit. What scenario would we use the Back End Limit? Thank you.