Debt-to-Income Ratio for Conventional Loans
The debt-to-income ratio for conventional loans measures how much of your monthly income goes toward debt payments, including the new mortgage. Fannie Mae sets clear limits that lenders use to assess qualification.
What Is the Debt-to-Income Ratio?
The debt-to-income (DTI) ratio compares your total monthly debt obligations to your stable monthly income. Lenders calculate it as part of qualifying for a conventional mortgage backed by Fannie Mae.
The ratio has two parts: total monthly obligations divided by total monthly income. Obligations include the proposed mortgage payment plus other debts like car loans, credit cards, and student loans.
Maximum DTI Ratios for Conventional Loans
Fannie Mae sets different limits depending on how the loan is underwritten.
- Manually underwritten loans: The maximum total DTI ratio is 36% of stable monthly income. This can rise to 45% when the borrower meets credit score and reserve requirements in the Eligibility Matrix.
- Loans underwritten through Desktop Underwriter (DU): The maximum allowable DTI ratio is 50%.
See B3-6-02, Debt-to-Income Ratios for full details.
High LTV refinance transactions often have no maximum DTI requirement except under the Alternative Qualification Path.
Cash-out refinance transactions may have tighter DTI limits through DU. Borrowers without credit scores face additional requirements that can lower the maximum ratio. For loans involving improvements, such as HomeStyle Refresh, manually underwritten files may allow up to 45% DTI if all Eligibility Matrix criteria are met.
How Lenders Calculate Total Monthly Obligations
Lenders add up all recurring monthly debts that affect your ability to repay. This includes:
- The qualifying payment on the subject mortgage loan
- Payments on installment debts lasting more than ten months
- Revolving debt minimum payments
- Lease payments
- Alimony, child support, or maintenance payments due beyond ten months
- Net losses from rental properties
Payments on debts lasting ten months or less may still count if they significantly impact your finances. See B3-6-05, Monthly Debt Obligations for guidance.
Debts paid by others can sometimes be excluded if you provide 12 months of canceled checks or bank statements showing on-time payments by the other party. When a borrower is obligated on a non-mortgage debt but is not the party actually repaying it, the lender may exclude the monthly payment from the borrower’s recurring monthly obligations, provided the other party is not an interested party to the transaction. For mortgage debts paid by others, exclusion is possible if the paying party is obligated on the debt, there are no delinquencies in the most recent 12 months, and the borrower is not using rental income from the property to qualify.
Step-by-Step Process to Determine Your DTI
- Gather your gross monthly income from all stable sources used for qualification, such as wages, self-employment earnings, and other documented income.
- Identify every recurring monthly obligation that will appear on your credit report or loan application, including the proposed mortgage payment (principal, interest, taxes, insurance, and any HOA fees).
- Add payments on installment debts with more than ten months remaining, revolving account minimum payments, lease payments, and court-ordered obligations like alimony or child support extending beyond ten months.
- Include any net rental losses and other significant short-term debts that could affect repayment ability.
- Divide total monthly obligations by total monthly income and multiply by 100 to obtain the DTI percentage.
- Compare the result against the applicable limits for manual underwriting or DU.
If new debts surface or income changes after initial underwriting, lenders recalculate the DTI. If the new DTI exceeds 45% on a manual loan or 50% on a DU loan, the file is typically ineligible. Loans that stay within limits but cross the 36% threshold must meet higher credit and reserve standards. DU loans require resubmission when changes fall outside tolerances. See B3-6-02, Debt-to-Income Ratios for re-underwriting steps.
Documents Checklist for DTI Verification
- Recent pay stubs covering at least 30 days and W-2 forms or tax returns for the prior two years to confirm income stability.
- Complete credit report showing all open accounts, balances, and payment histories.
- Statements for revolving accounts, installment loans, leases, and student loans.
- Divorce decree, separation agreement, or court order for alimony, child support, or maintenance obligations.
- Twelve months of canceled checks or bank statements for any debts paid by another party.
- Rental property documentation including leases, mortgage statements, and tax returns to calculate net income or loss.
- Bank statements or asset documentation supporting reserves when DTI exceeds 36% on manual loans.
All credit documents must generally be no more than four months old on the note date.
Worked Example of DTI Calculation
Suppose your gross monthly income is $8,000. Your proposed mortgage payment (principal, interest, taxes, insurance) is $2,200. You also have a $350 car payment and $150 minimum on credit cards.
Total obligations = $2,200 + $350 + $150 = $2,700.
DTI = $2,700 ÷ $8,000 = 33.75%.
This stays comfortably under the 36% manual limit and well below DU allowances. The calculation uses only stable monthly income and documented recurring obligations, excluding any voluntary payments or debts fully paid by others with proper documentation.
Common Mistakes That Affect DTI
- Overlooking short-term debts that still significantly impact cash flow even when ten months or less remain.
- Failing to document debts paid by others with twelve months of payment history, leading to unnecessary inclusion in the ratio.
- Using outdated income or liability figures that require re-underwriting and potential resubmission to DU.
- Ignoring net rental losses from other properties, which must be added to obligations.
- Assuming all revolving debt minimum payments are fixed without verifying current statements.
- Not accounting for new subordinate financing on the subject property, which triggers recalculation.
How DTI for Conventional Loans Compares to Alternatives
Conventional loans follow Fannie Mae guidelines with maximums of 36% (manual, extendable to 45%) or 50% (DU). Other loan types may apply different standards; for instance, some government-backed programs use their own liability calculations, including specific treatment of deferred obligations and student loans. High LTV refinance options under Fannie Mae generally remove maximum DTI requirements except on the Alternative Qualification Path. Borrowers should review the specific underwriting method—manual versus automated—to understand which limit applies.
Why DTI Matters for Approval
A lower DTI shows you have room in your budget for the mortgage. Conventional guidelines balance this with credit scores, reserves, and loan-to-value ratios to determine overall risk.
Requirements can vary slightly by lender program, but Fannie Mae rules provide the baseline for most conventional loans. If high balances are affecting your ratio, ask about credit improvement options that may help strengthen the overall application.
See B3-6-02, Debt-to-Income Ratios and B3-6-05, Monthly Debt Obligations for complete details.
Frequently asked questions
What is the highest DTI allowed on a conventional loan?
DU underwritten conventional loans allow up to 50% DTI. Manually underwritten loans start at a 36% maximum but can reach 45% when credit score and reserve requirements are met per the Eligibility Matrix.
How do I calculate my debt-to-income ratio?
Add your proposed mortgage payment to all other monthly debts such as car loans, credit cards, and student loans. Divide that total by your gross monthly income. The result is your DTI ratio.
Can debts paid by someone else be excluded from DTI?
Yes. If another party pays a non-mortgage debt and you provide 12 months of proof showing on-time payments, the lender may exclude it. The same applies to certain mortgage debts under specific conditions.
What happens if my DTI changes after underwriting?
Lenders recalculate the ratio. If it exceeds 45% on manual loans or 50% on DU loans, the file usually becomes ineligible. Smaller changes may require re-underwriting or meeting stricter credit and reserve rules.
Does alimony count toward my DTI?
Court-ordered alimony, child support, or maintenance payments expected to last more than ten months are included in monthly obligations. Alimony can sometimes be deducted from income instead of added to debt.