Front-End and Back-End DTI
Lenders split debt-to-income into two figures because housing and total debt tell them different things — one about whether the specific mortgage payment fits, the other about whether the whole financial picture leaves enough breathing room.
Formulas
Back-end DTI = Total monthly debt ÷ Gross monthly income
The 28/36 rule: front-end ≤ 28%, back-end ≤ 36%
Gross income is the figure lenders use throughout — income before tax and any other deduction, not the take-home pay that actually lands in a bank account. This consistently produces a lower DTI percentage than a calculation based on take-home pay would, which is worth knowing before comparing a lender's figure against your own household budget math.
What Counts as Debt and What Does Not
DTI counts only debt obligations with a fixed, recurring payment. Ordinary living expenses, however large, are not part of the calculation.
Counted: fixed monthly obligations
Mortgage or rent, car loans, student loans, personal loans, minimum credit card payments, child support and alimony, and any other debt appearing on a credit report with a required monthly payment.
Not counted: everyday living costs
Groceries, utilities, insurance premiums other than homeowners or mortgage-related insurance, phone bills, subscriptions, and general discretionary spending — none of it factors into DTI, however large a share of the budget it takes.
A gray area: credit cards paid in full
Lenders generally count the minimum payment on a credit card balance even if you pay it in full every month, since the calculation looks at the balance reported to the credit bureau at any given moment, not your personal payment habit.
Lowering DTI Before Applying
Two levers move DTI: the debt side and the income side, and the debt side almost always moves faster. Paying off or paying down a car loan or a credit card balance close to full removes its monthly payment from the calculation entirely, which is a larger and quicker DTI improvement than a raise usually produces.
Consolidating several smaller debts into one loan with a lower combined monthly payment can also help, provided the new payment is genuinely lower than the sum of what it replaces — a longer term at a similar or higher rate can lower the monthly figure while increasing total interest paid, which is worth weighing against the DTI benefit alone.