How Is Debt to Income Ratio Calculated? (2026 Formula)

The two DTI formulas

Front-end DTI (housing ratio):

Front-end DTI = (Total monthly housing payment) / (Gross monthly income)

Where total monthly housing payment includes:

• Mortgage principal and interest (P&I)
• Property tax (annual / 12)
• Homeowners insurance premium (annual / 12)
• Mortgage insurance (PMI, MIP, or FHA UFMIP financed monthly)
• HOA dues (monthly)
• Flood insurance if required

Back-end DTI (total debt ratio):

Back-end DTI = (Total monthly housing payment + All other monthly debt payments) / (Gross monthly income)

Where “all other monthly debt payments” includes:

• Minimum monthly credit card payments (the contractual minimum from each cardmember agreement)
• Monthly auto loan or lease payment
• Monthly student loan payment (per program-specific rules)
• Monthly personal loan or installment loan payment
• Monthly alimony or child support PAID (per court order)
• Co-signed debt where you cannot document 12+ months of timely payment by the primary obligor

The CFPB’s Ability-to-Repay rule at 12 CFR 1026.43 defines the obligation set. Fannie Mae and Freddie Mac follow this base and add specific selling-guide rules per B3-6-05 and section 5401 respectively.

What goes into the numerator: detailed line items

Credit cards: the minimum monthly payment from the most recent statement. Most issuers calculate minimums as the greater of $25 or 1 to 3 percent of balance. The exact minimum is documented in the cardmember agreement. Some lenders use the credit report’s monthly payment field, which may show the minimum or the actual recent payment, depending on the bureau.

Auto loans and leases: the contractual monthly payment per the loan agreement or lease. If a balloon payment is due within 18 months, lenders may amortize the balloon into a higher monthly payment for DTI.

Student loans: program-specific. Generally, lenders use the actual income-driven repayment amount (for Fannie/Freddie post-2023) or a percentage-of-balance calculation (0.5 percent for FHA, 1 percent for USDA). Deferred and forbearance loans use the assumed-payment percentage.

Personal loans: the contractual monthly payment per the promissory note. Loans with 10 or fewer payments remaining can typically be excluded under GSE rules.

Alimony and child support PAID: included per court order or written separation agreement. Voluntary support payments without a court order generally are NOT included.

Co-signed debt: contingent liability rules apply. If the primary obligor has paid for 12+ months from a non-shared bank account, exclusion is possible. Otherwise, the payment is added to DTI.

What does NOT go into the numerator

These are explicitly excluded from standard back-end DTI calculation:

• Current rent payment (when applying for a mortgage; the proposed PITI replaces it).
• Utility bills (electric, gas, water, internet, phone, streaming).
• Health insurance premiums (employee contribution).
• Auto insurance.
• Voluntary retirement contributions (401k, 403b, 457).
• Voluntary IRA contributions.
• Childcare costs.
• Tax withholding (federal, state, FICA).
• Groceries, gas, dining, entertainment, all variable household spending.
• Income tax owed (separate qualification issue under 12 CFR 1026.43; affects ability to repay but not DTI).

Gross income: what counts and how to document it

Salary and wages: base pay before taxes, withholdings, and voluntary deductions. Documented by W-2 and recent paystubs.

Overtime and bonus: 2-year average required. Documented by prior 2 years W-2s plus current paystubs. If the bonus or overtime decreased over the 2-year period, the lender may use the lower amount or exclude entirely.

Commission: 2-year average from federal tax returns. If commission is over 25 percent of total income, additional 2-year documentation requirements apply.

Self-employment income: 2-year average net income from federal tax returns (Schedule C for sole proprietors, Schedule E for rentals, K-1 for partnerships/S-corps). Documentation requirements in Fannie Mae Selling Guide B3-3.4.

Investment income: dividends, interest, capital gains (excluding one-time events). 2-year history typical. Cannot include retirement-account growth not received as distribution.

Rental income: Schedule E from prior 2 years, with 75 percent of gross rent counted (25 percent vacancy/expense adjustment per Fannie Mae).

Social Security, retirement, pension: current monthly amount, no gross-up unless the income is not taxable (gross-up of 1.15x or 1.25x is allowed in some programs).

Alimony and child support RECEIVED: court order or written agreement, 6-month receipt history, 3-year continuation probability. Conservative treatment.

Worked example 1: salaried borrower

A borrower earning $95,000/year salary plus $5,000 average annual bonus over 2 years, with these obligations:

• Salary: $7,917/month gross.
• Bonus: $417/month (2-year average).
• Total gross income: $8,334/month.
• Credit card minimums: $185 (across 3 cards).
• Auto loan: $445/month.
• Student loans IDR: $215/month (Fannie/Freddie use actual; FHA uses greater of actual or 0.5 percent of $42,000 balance = $210, so $215 wins).
• No alimony or child support.
• Applying for $340,000 mortgage at 7 percent, 30-year. PITI estimated $2,460.

Front-end DTI: $2,460 / $8,334 = 29.5 percent.

Back-end DTI: ($2,460 + $185 + $445 + $215) / $8,334 = $3,305 / $8,334 = 39.7 percent.

Both ratios are within conventional, FHA, and VA caps. Likely approval.

Worked example 2: self-employed borrower

A freelance graphic designer with:

• Year 1 net Schedule C income: $72,000.
• Year 2 net Schedule C income: $84,000.
• 2-year average net income: $78,000/year = $6,500/month gross.
• Credit cards: $310/month.
• Auto: $0 (owned outright).
• Student loans: $0 (paid off).
• No other debt.
• Applying for $310,000 mortgage at 7 percent, 30-year. PITI estimated $2,230.

Front-end DTI: $2,230 / $6,500 = 34.3 percent.

Back-end DTI: ($2,230 + $310) / $6,500 = $2,540 / $6,500 = 39.1 percent.

Note: if Year 2 income had been LOWER than Year 1, the lender uses the 2-year average. If Year 2 was significantly lower (declining trend), lenders may use only Year 2 figures or may require explanation. The Fannie Mae Selling Guide B3-3.4 covers self-employment trend analysis.

Worked example 3: borrower with rental income

A borrower owns a rental property in addition to applying for primary mortgage:

• Salary: $6,200/month gross.
• Rental property: gross rent $1,800/month, PITI $1,400/month, other expenses $150/month.
• Net rental cash flow: $1,800 minus $1,400 PITI minus $150 expenses = $250/month positive.
• Lender uses 75 percent of $1,800 gross rent = $1,350. Subtract rental PITI and expenses ($1,550). Net for DTI: $1,350 minus $1,550 = minus $200/month (subtracted from income or added to debt).
• Total qualifying income: $6,200 minus $200 = $6,000/month gross.
• Credit cards: $90/month.
• Applying for $250,000 primary mortgage at 7 percent, 30-year. PITI estimated $1,810.

Front-end DTI: $1,810 / $6,000 = 30.2 percent.

Back-end DTI: ($1,810 + $90) / $6,000 = $1,900 / $6,000 = 31.7 percent.

Healthy ratios. The rental property’s mild negative cash flow is absorbed.

Worked example 4: variable-income borrower with commission

A real estate agent with:

• W-2 wages: $0 (1099 contractor with self-employed status OR licensed agent’s W-2 if employed by a broker).
• 1099 income: Year 1 $115,000 gross, $85,000 net after Schedule C deductions. Year 2 $128,000 gross, $96,000 net.
• 2-year average net: $90,500/year = $7,542/month gross.
• Credit cards: $440/month (high utilization on agent business expenses).
• Auto: $0.
• Student loans: $0.
• Applying for $360,000 mortgage at 7 percent. PITI estimated $2,560.

Front-end DTI: $2,560 / $7,542 = 33.9 percent.

Back-end DTI: ($2,560 + $440) / $7,542 = $3,000 / $7,542 = 39.8 percent.

Paying down the $440/month credit card minimums to $100 would drop back-end DTI to 35.3 percent.

Note: real estate agents face additional scrutiny under Fannie Mae self-employed guidelines. Recent industry-wide income volatility may require declining-income explanation.

How to estimate your DTI before applying

Step 1: List all monthly debt minimum payments. Pull your latest statements for each credit card, auto loan, student loan, personal loan. Use the minimum, not what you usually pay.

Step 2: Add any alimony or child support paid per court order.

Step 3: Calculate gross monthly income. Use base salary plus 2-year average of bonus/commission/overtime. For self-employed, use 2-year average net Schedule C/E/K-1 income.

Step 4: Estimate proposed PITI. Use a mortgage calculator with: loan amount, interest rate, loan term, property tax (county-specific, typically 0.5 to 2.5 percent of home value annually), homeowners insurance (typically 0.3 to 0.5 percent annually), HOA dues if applicable.

Step 5: Compute front-end and back-end DTI.

Step 6: Compare against program caps. Conventional 45 percent typical, 50 with compensating factors. FHA 43 standard, 50 with compensating factors. VA 41 guideline. USDA 41 strict.

Three DTI calculation mistakes consumers commonly make

Mistake 1: Using net income instead of gross. Net (after-tax) is roughly 70 to 80 percent of gross. Using net inflates DTI by 25 percent or more, leading borrowers to think they cannot qualify when they actually can.

Mistake 2: Using actual payments instead of minimums. If you pay $300/month on a $5,000 credit card balance but the minimum is $125, DTI uses $125. Your aggressive payment behavior does not penalize qualification.

Mistake 3: Forgetting the proposed PITI replaces rent. Adding both current rent AND proposed mortgage payment inflates DTI dramatically. Only the proposed PITI is in the calculation.

When DTI is borderline: how lenders find ways to qualify

Even with DTI above program caps, qualification is sometimes possible through:

• Compensating factors. FICO 720+, cash reserves of 3+ months PITI post-close, low payment shock relative to current rent, stable 2+ years of employment, additional non-qualifying income.
• Non-occupant co-borrower. A parent or relative who is not living in the home can co-sign and add their income/credit to the application. Conventional and FHA allow this; VA does not (must be spouse).
• Excluding 10-or-fewer-payment installment debts. Paying off short-term auto or personal loans to drop their payment from DTI.
• Refinancing existing debt to lower minimum payment. Refinancing a high-rate personal loan to a longer term reduces the monthly payment used in DTI even if total cost rises.

Re-checking DTI through underwriting

DTI is re-verified at three points in the mortgage process:

1. Application. Self-reported and bureau-pulled credit report.
2. Underwriting. Full document review (pay stubs, tax returns, bank statements, credit report).
3. Pre-funding QC. Final credit report pulled within 10 days of closing. New debts added during this window can move DTI and even disqualify the loan.

Do not take on new debt (auto loan, new credit card, deferred-payment furniture) during underwriting. Even small new monthly obligations can push DTI over the cap and require re-underwriting.

Authoritative sources

• CFPB, Qualified Mortgage rule (12 CFR 1026.43)
• CFPB, Debt-to-income ratio explainer
• Fannie Mae Selling Guide B3-3 Income Assessment
• Fannie Mae Selling Guide B3-6 Liability Assessment
• Freddie Mac Single-Family Seller/Servicer Guide section 5401
• HUD, FHA Handbook 4000.1
• VA Lenders Handbook M26-7
• USDA Single Family Housing Guaranteed Loan Program
• HUD, Housing Counseling Agencies

Sibling questions

• What DTI ratio is too high for mortgage?
• How to lower your debt to income ratio?
• Does debt to income include rent?
• Does debt to income include student loans?
• Does debt to income ratio affect mortgage rate?
• Should I pay off debt before buying a house?

Related tools

• Credit card payoff calculator
• Debt management plan calculator
• Balance transfer calculator

Frequently asked questions

What is the formula for debt-to-income ratio?

DTI ratio equals total monthly debt payments divided by gross monthly income, expressed as a percentage. The numerator is the sum of minimum required monthly payments on all debts (credit cards, auto, student loans, personal loans, mortgages or rent for non-mortgage applications, alimony, child support). The denominator is gross income before taxes. Two versions exist: front-end DTI is housing payment only, back-end DTI is all debt.

Should I use gross or net income for DTI?

Gross income, before tax. Mortgage lenders, credit card issuers, and personal lenders all use pre-tax income because tax withholding varies by household and federal/state laws. Gross income is calculated as base salary plus consistent bonus and overtime (2-year average required), commission (2-year average), alimony received (court-ordered), child support received, rental income (per Schedule E with 25 percent vacancy adjustment), and SSI/SSDI/retirement (current monthly amount).

Should I use minimum payments or actual payments for DTI?

Minimum payments. The DTI calculation uses the minimum monthly payment due on each debt as reported on the credit report or in the cardmember/loan agreement, not what you typically pay. For credit cards, this is the printed minimum from the most recent statement. For installment loans, this is the contractual monthly payment. Lenders use minimums because they reflect the binding obligation, not voluntary aggressive payoff.

How do I calculate DTI as a freelancer or self-employed person?

Lenders use 2-year average net income from Schedule C (sole proprietors) or K-1 distributions plus W-2 wages (S-corps, partnerships), as documented on the prior 2 years of federal tax returns. Some lenders accept 1-year tax returns with profit-and-loss statement for businesses operating 2+ years. Recent bank-statement-only loans allow gross deposits with expense factor. The 12 CFR 1026.43 Ability-to-Repay rules permit reasonable verification methods.

Is property tax included in DTI?

Yes, for mortgage qualification. Property tax is part of PITI (principal, interest, taxes, insurance), and PITI is the housing payment used in both front-end and back-end DTI. Annual property tax is divided by 12 to produce the monthly amount. Homeowners insurance, HOA fees, and mortgage insurance (if applicable) are also included in PITI per Fannie Mae Selling Guide B3-6-04. For owner-occupied properties, this is straightforward; for rental properties, Schedule E flows are used.