Bank Statement Mortgage History: 12 vs. 24 Months of Deposits

The Quick Read: The 12-month window reflects only your most recent year, so it favors borrowers whose deposits are climbing. The 24-month window averages two years, so it favors borrowers whose income swings with the season or the job cycle. Neither window rescues a falling trend, and some programs set the window for you instead of offering a choice.

• Rising deposits usually look stronger on a 12-month average.
• Seasonal or lumpy deposits usually look steadier across 24 months.
• Falling deposits are a red flag under either window.
• Deposit quality and the expense factor often move the coverage figure more than the window does.
• Occupancy decides the paperwork: owner-occupied files are consumer mortgages, while non-owner-occupied rentals are business-purpose.

The honest answer is that the two windows serve different income stories. A 12-month file is for the borrower who wants the latest year to speak for itself. A 24-month file is for the borrower who wants a longer track record to do the talking. Across the lenders Lendmire works with, the window is a program rule as often as it is a borrower’s choice, so the first step is learning what a given program allows.

Side-by-Side

The table below reflects published industry norms for the longer window, set against the 12-month documentation Lendmire’s wholesale network commonly works with. Details vary by program sheet.

The rows on growth, decline, and seasonality are our own read of the arithmetic. Underwriters do not formally rank one window above the other, so treat any claim that one is simply preferred with suspicion.

How the Math Actually Works

Qualifying income comes from deposits, not traditional personal-income documentation. Scotsman Guide describes a self-employed borrower giving a non-QM lender 12 to 24 months of personal or business statements. The lender then applies an expense factor, with 50% as its example, and may accept a profit-and-loss statement or an expense statement from a third-party tax professional instead.

The steps run in a simple order:

1. The lender totals eligible deposits across the window.

2. Transfers between your own accounts and other non-income credits are screened out.

3. On business accounts, an expense factor reduces the total.

4. The result is divided by 12 or by 24.

5. That monthly figure feeds the debt-to-income review.

Step four is the entire structural difference. The divisor changes, and so does everything that falls inside it. No lender should promise a universal expense factor, because each program sets its own.

When 12 Months Is the Better Fit

Choose the shorter window if your income has been climbing. A contractor who landed bigger accounts this year, a consultant who left an employer mid-stream, or an owner whose first year was thin will often see a higher average on 12 months. Older, lower months simply stay out of the math.

It also suits a short self-employment history. If you have not been in business for two full years, the longer window may not be available at all.

The tradeoff is exposure. One unusual month carries more weight in a 12-month divisor. A single big deposit lifts the number, and one slow quarter drags it down. If your best year was an outlier, the shorter window can flatter you on paper and then invite harder questions from the reviewer.

When 24 Months Is the Better Fit

Choose the longer window if your deposits rise and fall with the calendar. Landscapers, event businesses, and seasonal retailers often look steadier across two cycles than across one. The extra year smooths the peaks and troughs.

It also helps if your latest year contained a one-off dip. A medical leave or a lost contract looks smaller when averaged against a strong prior year. Larger loans, at the upper end of the roughly $125,000 to $3,500,000 range, often draw closer scrutiny of income history, and a longer record can reassure a reviewer.

The cost is dilution. If your income grew, older, lower months pull the average down. And a weak stretch in either year counts. Two years of statements also mean more pages to assemble and more deposits to explain.

Deposits and Expense Factor Can Matter More Than the Window

Many borrowers fixate on 12 versus 24 and overlook the two inputs that often move the number further. The first is deposit quality. Gifts, loan proceeds, and transfers do not count as income. The CFPB’s small-entity compliance guide says a creditor relying on account inflows must confirm they are the consumer’s personal income, which is why those deposits get screened out.

The second is the expense factor. A business account is treated as gross revenue, so a higher factor shrinks qualifying income no matter which window you pick. Programs vary, and an accountant-prepared ratio can sometimes replace the default. The strongest files we see arrive with clean, consistent account sets and a written explanation for any large deposit.

Edge Cases Worth Knowing

Switching banks or accounts. Statements should be complete and consecutive. A mid-window switch is manageable when both account histories are included, but gaps invite questions.

A single windfall. One large deposit can distort either window. Expect it to be excluded or explained.

Seasonal and growing at once. These pull in opposite directions. Running both calculations is the only reliable way to see which wins.

Falling income. Switching windows will not fix a downward trend. Reviewers look at direction regardless of divisor.

Whether you can choose. Some programs fix the window by loan size, credit tier, or product. Ask for both calculations where the program allows, and ask which one the lender will actually use. Lendmire’s piece How to Choose 12 vs 24 Months on a Bank Statement Mortgage walks through that decision in more depth.

Occupancy Decides the Rulebook

What you are buying matters as much as the window. An owner-occupied purchase or refinance, including a second home, is a consumer mortgage, and TRID disclosures apply. Leverage on a primary residence can reach up to 90% LTV on a purchase or rate-term refinance through select lenders, while owner-occupied cash-out generally tops out at 80% LTV, or 75% with an accountant-prepared ratio, depending on loan size and credit.

A bank statement loan on a non-owner-occupied rental, including a short-term rental, is business-purpose and exempt from TRID. Investment cash-out typically tops out near 75% LTV, and investment purchase leverage varies by lender. Federal rules treat credit for acquiring a rental as business-purpose in many cases. Regulation Z’s business-purpose exemption and the CFPB’s commentary set out where the line falls, and a loan to a natural person on a small rental depends on the facts. Pricing and payment figures live only in the calculator.

Bank Statement Loans vs. Property-Income Loans

A bank statement file qualifies your personal cash flow. A property-income file, which is what a DSCR loan is, is reviewed on the property’s rent covering its payment. Investors with several loans often hit the personal debt-to-income ceiling on bank statement files, while a property-income structure reviews each property on its own merits. If you are weighing the two, Lendmire’s piece DSCR Loan Vs Bank Statement Loan For Investors covers it, and the complete DSCR loans guide explains the property-income side. Bank statement loans qualify on documented income under the applicable program, subject to lender guidelines.

Key Terms Defined

Lookback window: the number of consecutive months of statements a lender averages, usually 12 or 24.

Expense factor: the percentage a lender subtracts from business deposits to estimate net income.

Eligible deposits: recurring credits that count as your income, after transfers, gifts, and loan proceeds are removed.

Profit-and-loss statement: a summary of revenue and expenses, sometimes accepted in place of the default expense factor.

Ability to repay: the lender’s duty to verify that you can afford the loan using reliable records.

A Balanced Verdict

Pick 12 months when your trend is up and your history is short. Pick 24 months when your income is seasonal or one recent stretch was unusually weak. If income is flat, either works, and the longer window adds evidence of stability. If income is falling, neither window helps, and the better move is usually to wait, build reserves, or reconsider the structure.

And remember the limits. Credit, equity, reserves, and deposit quality often decide the outcome more than the window. If you are self-employed and want to see how the numbers work, Lendmire can help you compare bank statement loan options based on your deposits, the property, credit profile, leverage, and your goals. Qualification is subject to lender guidelines, and none of this is a commitment to lend. Tax treatment varies; consult a qualified professional.

About Lendmire

Lendmire (NMLS# 2371349) is a DSCR-focused mortgage broker that helps arrange investor financing across 41 markets, including Washington, D.C., through wholesale and investor-lending channels. DSCR eligibility is generally reviewed by the lender around the property’s rental income rather than personal income documentation, subject to lender guidelines — which works for self-employed investors, LLC operators, and portfolios above four financed properties. Scotsman Guide named Lendmire a Top Mortgage Workplace in both 2025 and 2026.

References

1. Scotsman Guide, “Rev Up the Engine for Non-QM Lending”

2. CFPB ATR/QM Small Entity Compliance Guide (April 2021 edition)

3. eCFR, 12 CFR 1026.3