How Lenders Calculate Your Income if It’s Not Fixed

 

If your income changes from month to month, you’ve probably wondered: how do lenders decide what counts as my income? The answer is through averaging. Lenders don’t use your highest-earning month or your best year—they use a conservative calculation to determine what they believe is sustainable.

In this article, we’ll explain the methods lenders use, why it matters for your mortgage approval, and real-world examples that show how the numbers work.

If you’re just joining this series, start with our Complete Guide on Variable Income and Mortgage Qualification for a big-picture overview, or see What Documents Do You Need if You Have Variable Income? for a list of the paperwork that feeds into these calculations.

 

Why Income Averaging Matters

Lenders want to avoid approving a loan based on income that’s unusually high for a short period of time. By averaging your income:

• Stability is emphasized: Fluctuations are smoothed out.
• Risk is reduced: Borrowers aren’t approved for homes they can’t consistently afford.
• Continuity is tested: Only income likely to continue is counted.

 

The Two Main Methods

12-Month Average

• Used when income is stable or rising.
• Reflects the most recent year’s performance.
• Often benefits borrowers who had a strong year or are trending upward.

24-Month Average

• Used when income is declining or inconsistent.
• Spreads earnings over two years to get a more conservative figure.
• Protects the lender from relying on a recent high year that may not repeat.

 

Example Chart: 12-Month vs. 24-Month Average

Year/Period	Gross Income	Calculation	Resulting Qualifying Income
Last 12 Months	$96,000	÷ 12	$8,000/month
Last 24 Months	$168,000	÷ 24	$7,000/month

In this case, if income is steady or rising, a lender may use $8,000/month. But if income dropped in year two, they’ll lean on the 24-month average of $7,000/month.

 

How Different Income Types Are Treated

Not all income is counted the same way. Here’s how lenders typically handle variable income:

• Overtime and Bonuses: Must be consistent for 2 years to be fully counted.
• Commission: Averaged over 12 or 24 months; lenders may look at industry history if you’re new.
• Seasonal Work: Allowed if it shows a consistent annual pattern.
• Self-Employed Income: Based on net income from tax returns, not gross revenue.

 

What If Your Income Is Declining?

If your income is trending downward, lenders will almost always use the lower average, which can reduce your qualifying amount. But that doesn’t mean homeownership is off the table. There are alternative loan programs that can help:

• Bank Statement Loans: Instead of tax returns or W-2s, lenders use your personal or business bank statements (typically 12–24 months) to calculate average monthly deposits.
• DSCR Loans (Debt Service Coverage Ratio): For real estate investors, qualification is based on the property’s cash flow—not your personal income.
• Non-QM Loans (Non-Qualified Mortgage): Broader category that includes programs like asset depletion, 1099-only loans, or stated income.
• Co-Borrowers or Co-Signers: Adding a co-borrower with stable income can increase your qualifying power.

These options usually come with higher rates or larger down payments, but they can keep your path to homeownership open.

 

Real-Life Example Scenarios

Scenario 1: Commission-Based Sales Rep

• Year 1: $90,000
• Year 2: $120,000
• Average (24 months): $105,000 ÷ 24 = $8,750/month
• Result: Approved using the higher two-year trend, since income was increasing.

 

Scenario 2: Nurse With Overtime and Per Diem Pay

• Base Salary: $70,000
• Overtime + Per Diem (consistent for 2 years): $15,000 annually
• Qualifying Income: $85,000/year or $7,083/month

 

Scenario 3: Freelancer With Temporary Maternity Leave

• Income History: Normally earns about $75,000 a year. Took three months off for maternity leave in year two but then went back to work at the same level.
• Documentation Provided: Tax returns, bank statements, and a short letter explaining the leave, along with proof of returning to work.
• Outcome: Approved. Because the leave was temporary and income resumed, the lender did not count those three months against her. They used her normal income for qualifying.

 

FAQs About Income Calculation

Q: Will lenders always use the lower average?
A: Not always. If your income is rising steadily and you can document the trend, lenders may use a 12-month average.

Q: What if I just switched to commission income?
A: Most lenders want 2 years of commission history. If you changed roles in the same industry, exceptions may apply.

Q: Do all lenders calculate income the same way?
A: No. While guidelines are similar, some lenders are more flexible than others, especially with strong documentation.

Q: What if my income is declining and I can’t qualify traditionally?
A: You may be able to explore bank statement loans, DSCR programs, or other non-QM options that use alternative qualifying methods.

 

Final Thoughts

If your income isn’t fixed, lenders will average it to find a reliable number. Whether they use a 12-month or 24-month approach depends on your stability, industry, and documentation.

Even if your income has declined, options exist. From bank statement loans to DSCR programs, there are creative financing solutions that can help you qualify.

For the full picture, revisit our Complete Guide on Variable Income and Mortgage Qualification. Or, if you’re preparing paperwork now, see What Documents Do You Need if You Have Variable Income? to get organized.

Check out 5 Ways to Strengthen Your Mortgage Application With Variable Income where we’ll give you strategies to make your file stand out.

Disclaimer This information is based on current Fannie Mae guidelines as of today. Mortgage rules and program requirements can change, and different lenders may interpret them differently. Always check with a qualified mortgage professional for the most up-to-date guidance on your specific situation.