Quick Answer: Bank statement loan underwriters total your deposits over 12-24 months, subtract an expense factor (typically 10%-50% depending on your business type and documentation), and divide the result by the number of months to arrive at your qualifying monthly income.
If you’re self-employed, your tax returns probably understate what you actually earn. That’s the whole reason bank statement loans exist: they let underwriters look at what actually landed in your accounts instead of your adjusted gross income after deductions. But “we use your deposits” isn’t the full story, and a lot of borrowers get surprised by how much lower their qualifying income ends up being than their gross revenue.
Here’s the actual math underwriters run, line by line, so you can estimate your number before you ever submit an application.
What Underwriters Actually Pull From Your Bank Statements
Underwriters don’t just add up every deposit and call it income. They start by separating your statements into personal accounts and business accounts, because the calculation differs for each.
Business Accounts
For business accounts, the underwriter totals all qualifying deposits over the statement period, then applies an expense factor to account for the cost of running the business (payroll, supplies, rent, and so on) before that revenue becomes personal income.
Personal Accounts
If you deposit business income directly into a personal account, underwriters generally treat 100% of qualifying deposits as income, since there’s no assumed business overhead sitting underneath a personal account. This is one reason some self-employed borrowers deposit revenue into personal accounts when it makes sense for their business structure.
The Expense Factor: How It Actually Works
The expense factor is the single biggest variable in a bank statement loan calculation, and it’s the part most borrowers underestimate. Lenders apply a default expense ratio to business account deposits, then subtract that percentage before counting anything as usable income.
Standard Expense Factor Ranges
Default expense factors commonly run between 10% and 50%, depending on the lender’s guidelines and your industry. A service-based business with low overhead (consulting, real estate agents, freelance professionals) might land at the lower end. A business with significant physical overhead – inventory, equipment, staffing – typically lands higher.
So if your business account shows $600,000 in qualifying deposits over 12 months and the lender applies a 40% expense factor, your usable income is $360,000 for the year, or $30,000 per month, before any further underwriting adjustments.
Overriding the Default With a CPA Letter or P&L
Most bank statement programs allow you to submit a CPA-prepared profit and loss statement or a signed letter from your accountant specifying a lower expense ratio if your actual overhead is thinner than the default assumption. This can meaningfully increase your qualifying income, but the lender will usually still compare that figure against your deposit history for reasonableness. An unsupported number that’s dramatically lower than industry norms will likely get questioned or capped.
Step-by-Step: Estimating Your Own Number
You can run a rough version of this calculation yourself before applying.
1. Pull 12 or 24 Months of Statements
Bank statement programs typically use either 12 or 24 months of statements. A 24-month average tends to smooth out seasonal swings, which helps if your business had a slow stretch. A 12-month average can work better if your most recent year was your strongest.
2. Identify Qualifying Deposits
Underwriters exclude certain deposits from the calculation, including transfers between your own accounts, loan proceeds, and one-time deposits that don’t reflect recurring business activity. Large, irregular deposits often get flagged and require a written explanation, and if they can’t be documented as legitimate recurring revenue, they may be excluded entirely.
3. Watch for NSFs and Negative Days
Frequent overdrafts or negative balance days are a red flag for underwriters and can affect both approval and pricing, separate from the income calculation itself. A handful of NSFs won’t necessarily sink a file, but a pattern of them raises questions about cash flow stability.
4. Apply the Expense Factor
Total your qualifying deposits, subtract the applicable expense factor, and divide by the number of months in your statement period. That’s your estimated qualifying monthly income before debt-to-income ratio calculations are applied.
Common Mistakes That Shrink Your Qualifying Income
A few patterns show up repeatedly in bank statement files that reduce the final number more than borrowers expect.
Mixing personal and business expenses in the same account makes it harder for an underwriter to isolate qualifying revenue cleanly, sometimes triggering a higher default expense factor rather than a lower one. Inconsistent monthly deposits without an explanation can also work against you, since underwriters are looking for a reasonably stable pattern, not just a high total. And switching banks or account structures partway through the lookback period can complicate the calculation and may require additional documentation to piece together a full picture.
It’s also worth knowing that bank statement loans are one piece of a larger Non-QM toolkit. Borrowers who don’t quite fit the deposit-based model – for example, those with significant assets but inconsistent cash flow, or investors financing property based on rental income rather than personal income – often look at options like asset utilization or DSCR loans instead. You can see how these programs compare, including documentation differences, in mbanc’s guide to Non-QM trades.
Because bank statement loans fall under Non-QM guidelines, pricing runs higher than a conventional mortgage – generally in the range of approximately 125-300 basis points (1.25%-3.00%) above comparable conventional rates, depending on credit score and loan-to-value ratio. Borrowers with strong credit and solid deposit history tend to fall toward the lower end of that range. On a $400,000 loan, a 2.00% rate differential works out to a meaningful difference in the monthly payment, so it’s worth running the numbers against your actual qualifying income before deciding how much to borrow.
Frequently Asked Questions
How many months of bank statements do lenders typically require?
Most bank statement programs require either 12 or 24 consecutive months of statements. A 24-month average often smooths out seasonal income swings, while a 12-month average can help if your most recent year was your strongest.
Can I use a lower expense factor than the lender’s default?
In many cases, yes. If your CPA can provide a signed profit and loss statement or letter documenting a lower actual overhead percentage, the lender may use that figure instead of the standard default expense ratio, though it’s still typically reviewed against your deposit history for reasonableness.
Do personal bank statement deposits get treated differently than business deposits?
Generally, yes. Business account deposits usually have an expense factor applied to account for overhead, while qualifying deposits into a personal account are typically counted closer to 100%, since there’s no assumed business expense sitting underneath a personal account.
Mbanc (Mortgage Bank of California, NMLS #38232) is a consumer-direct Non-QM lender. This content is for informational purposes only and does not constitute a commitment to lend. All loans subject to credit approval.