The Debt-to-Income (DTI) ratio is one of the primary underwriting criteria lenders use to assess your ability to manage monthly payments and repay borrowed money.
Lenders evaluate two distinct DTI figures: 1. Front-End DTI (Housing Ratio): The percentage of income that goes strictly toward housing expenses (mortgage principal, interest, property taxes, homeowner's insurance, and HOA dues — commonly called PITI). 2. Back-End DTI (Total Debt Ratio): The percentage of income committed to ALL recurring monthly obligations (housing expenses plus student loans, auto loans, minimum credit card payments, child support, and personal loans).
For conventional conforming mortgages backed by Fannie Mae or Freddie Mac, the standard maximum back-end DTI is typically 43% to 45%, although borrowers with strong compensating factors (such as excellent credit scores or substantial cash reserves) may receive approval up to 50% through automated underwriting systems (AUS).