How to Calculate Average Monthly Deposits from a Bank Statement

Why Average Monthly Deposits Matter

Average monthly deposits is one of the most important numbers in bank statement underwriting. For self-employed borrowers, MCA applicants, and bank statement loan programs, it serves as the proxy for income — replacing the adjusted gross income figure that appears on tax returns.

Lenders use average monthly deposits to determine how much a borrower earns (adjusted for expense factors), whether that income can support the proposed loan payment, and whether the income is consistent or volatile.

Step 1: Identify the Statement Period

Before calculating anything, confirm the date range. A 3-month statement covering January through March is straightforward. But some lenders request 12 or 24 months, which means reviewing multiple statements and handling months with overlapping coverage.

For accuracy, always use complete calendar months only. Partial months skew the average.

Step 2: Total All Deposits in Each Month

Go through each statement and total every credit to the account. In this step, include everything — do not start excluding items yet. Sum all deposits for each month separately.

Example:

• January: $14,200 total deposits
• February: $13,800 total deposits
• March: $15,100 total deposits

Step 3: Identify and Exclude Non-Income Deposits

Not every deposit represents income. Lenders exclude items that are not evidence of earning capacity:

• Transfers from other accounts — Moving money from savings to checking does not create new income. Look for matching transfers in and out between dates.
• Loan proceeds — A $20,000 PPP loan deposit or personal loan disbursement is not recurring income and must be excluded.
• Insurance settlements or tax refunds — One-time receipts are not recurring income.
• Returned items — A chargeback reversal or returned payment going back to the account is not income.
• Investment or retirement distributions — May count depending on the loan program but need separate documentation.

Revised example after exclusions:

• January: $14,200 → exclude $2,000 transfer from savings = $12,200 qualifying deposits
• February: $13,800 → no exclusions = $13,800 qualifying deposits
• March: $15,100 → exclude $5,000 loan proceeds = $10,100 qualifying deposits

Step 4: Calculate the Monthly Average

Add the qualifying deposits for all months, then divide by the number of months.

Example: ($12,200 + $13,800 + $10,100) ÷ 3 = $12,033 average monthly deposits

Step 5: Apply the Expense Factor (For Non-QM Loans)

For bank statement mortgage programs and some business loans, lenders apply an expense factor to account for business operating costs. This factor varies:

• Service businesses (consulting, professional services): 50% factor → $12,033 × 50% = $6,017 qualifying income
• Product-based businesses: 25–35% factor typically
• Some lenders use a CPA-provided expense ratio instead of a flat percentage

For MCA underwriting, the expense factor step is usually skipped — lenders assess the gross deposit average and evaluate affordability based on the proposed daily payment relative to the daily deposit average.

Step 6: Check for Consistency

The average alone doesn't tell the full story. Lenders also evaluate the consistency of deposits:

• Is each month within 20–30% of the average? (Consistent)
• Is one month significantly higher, pulling up a weaker average? (Irregular — may be adjusted)
• Is there a clear upward or downward trend? (Trend matters as much as average)

A borrower with deposits of $25,000, $12,000, and $1,000 has a $12,667 average — but the declining trend is a serious concern that the average alone obscures.

Common Mistakes in Calculating Average Monthly Deposits

• Including internal transfers — Counting transfers between accounts inflates income and is a form of deposit manipulation
• Using incomplete months — A partial month at the start or end of a statement skews the average down
• Not excluding loan proceeds — A PPP loan or line of credit draw looks like income but is debt
• Averaging over too few months — 2 months may miss seasonal patterns; 12 months is more reliable

How AI Automates This Calculation

Manual deposit calculation across 12–24 months of statements with hundreds of transactions is time-consuming and error-prone. StatementScrub automates the entire process — it reads every transaction, classifies deposits, excludes identified transfers and loan proceeds, calculates monthly averages, and displays the results in a structured report in under 30 seconds.

The AI also flags months where unusual large deposits (potential one-time items) significantly affect the average, so you can make an informed judgment about whether to include or exclude them.

Example Calculation Summary

Bottom Line

Average monthly deposits is a calculated figure, not just a simple sum. Proper calculation requires identifying the statement period, totaling deposits by month, excluding non-income items, and verifying consistency. Automated tools eliminate the manual work and reduce the risk of calculation errors that could result in approving a loan the borrower can't afford — or denying one they can.