The two ratios
The front-end ratio is your full housing payment divided by gross monthly income. The housing payment includes principal and interest, property tax, homeowners and flood insurance, HOA or condo fees and any mortgage insurance. The back-end ratio adds every other debt that shows on your credit report or that you pay under a court order: car loans, student loans, minimum card payments, child support.
Which limits matter
- 28/36 is the classic guideline. Staying inside it leaves room in the budget for repairs and rising insurance.
- 43% is the figure many lenders still use as a working limit, and it is the most common cap on manually underwritten FHA and conventional files.
- Fannie Mae allows up to 50% when the loan is approved through its automated system, Desktop Underwriter. Manual underwriting is limited to 36%, or 45% with higher credit scores and reserves.
Why Florida buyers hit the limit sooner
Two homes with the same price can have very different ratios. A newer house inland with a low insurance quote might carry $300 a month in insurance, while an older coastal home can be $700 or more before flood coverage. Condo fees in older buildings have gone up as associations fund the reserves required by the condo safety laws passed since 2022. Every one of those dollars counts against you.
If you use a Florida Housing down payment assistance loan that has a monthly payment, such as the FL HLP second mortgage, that payment may also be counted in your back-end ratio.
Property tax should be estimated at your purchase price. The seller's bill reflects their assessed value and homestead cap, which do not transfer to you.
Questions
Do utilities and phone bills count in DTI?
No. Lenders count debts and housing costs, not living expenses like utilities, groceries or phone plans.
Is DTI based on take-home pay?
No. It uses gross income before taxes and payroll deductions.
Can I get a mortgage above 43% DTI?
Often yes, through automated underwriting with good credit and cash reserves. Fannie Mae allows up to 50% on loans approved by Desktop Underwriter.
- Fannie Mae Selling Guide B3-6-02: Debt-to-Income Ratios
- Florida Housing: homebuyer programs and down payment assistance
