How to Pick 12 or 24 Bank Statement Months When Income Just Rose

The Quick Read: When income has risen, the 12-month window usually produces the higher coverage figure because it leaves out older, lower months, but the right pick comes from calculating both windows on eligible deposits, checking that the rise is sustained, and confirming which window the lender’s program actually allows. A DSCR loan skips the question entirely, since it qualifies primarily on property-level rental income covering the payment, subject to lender guidelines.

• A real, sustained raise favors the shorter window. Older low months drag a longer average down.
• A brief spike favors neither window. Underwriters strip one-time deposits and question short runs of high ones.
• Flat, seasonal or lumpy income often favors 24 months, because a full cycle smooths out one strong or weak month.
• The window is often set by the program, so it is not always your decision.

What You Are Actually Choosing

A bank statement loan qualifies a borrower on documented income under the applicable program, subject to lender guidelines. The lender does not read a tax return. It reads deposits.

Qualifying income comes from averaging eligible deposits across a lookback window. The window is 12 consecutive months or, on programs that offer it, 24 consecutive months. The average, after the lender’s expense factor, becomes monthly income. That income feeds the debt-to-income calculation, which sets how much loan the file can support.

Investors usually meet this choice in two situations. The first is buying an owner-occupied home or second home while self-employed. The second is wanting a personal-income-tested loan on a rental because the title is individual or the rent is thin. Across Lendmire’s wholesale network, the baseline documentation is 12 months of business or personal statements. Some lender programs add a longer option. Others offer only one window.

Key Terms Defined

Lookback window: The number of consecutive months of statements the lender averages to find your income.

Eligible deposits: Deposits that count as earned income, after the lender removes transfers between your own accounts, refunds, loan proceeds, gifts and one-time items.

Expense factor: A percentage the lender applies to business-account deposits to account for the cost of running the business. It varies by lender and program.

Qualifying income: The monthly figure left after averaging and applying the expense factor. It is the number used in the debt-to-income test.

DTI: Debt-to-income ratio, which compares your monthly obligations to your qualifying income.

Letter of explanation: A short written note explaining a large or unusual deposit.

Why a Raise Changes the Math

A raise is the one situation where the two windows give clearly different answers. The 24-month window blends your old, lower months with your new, higher ones. The 12-month window sees only the recent stretch.

Picture an investor whose monthly deposits sat at an index of 100 for a full year, then stepped up to 150 and stayed there for the next twelve months. The 12-month average is 150. The 24-month average is 125. Before any expense factor, the shorter window shows income 20% higher.

An expense factor typically scales both windows by the same percentage. The 20% gap therefore survives it. That is why the window choice can move purchase capacity as much as a negotiation over the factor itself.

The reverse also holds. If last year was strong and this year slipped, the longer window can give the higher number. Underwriters still read the slope, so a real decline gets noticed under either window.

How Underwriting Treats the Statements, Step by Step

The process follows the same sequence on most files, whichever window applies.

1. Choose the account type. Options are business statements, personal statements, or a blend. Business deposits get an expense factor. Personal deposits usually count closer to full value, depending on the lender.

2. Collect every page of every account. The months must be consecutive. A missing month breaks the sequence and can force a restart.

3. Total the eligible deposits. The lender removes transfers, refunds, loan proceeds, gifts and one-offs. Large or unexplained deposits trigger letters of explanation.

4. Apply ownership percentage and the expense factor. If you own part of a business, only your share of its deposits counts.

5. Divide by the window length. The result is monthly qualifying income.

6. Check the trend. Underwriters look at direction as well as the average.

7. Underwrite the rest of the file. Credit, DTI, reserves, the property and title all still apply.

Only the documentation method changes. The ability to repay does not. Lendmire does not underwrite or approve loans. Lenders do, and each reads its own program sheet.

Worked Example: Two Kinds of Raise

The figures below are an index, not dollars. They are modeled assumptions for illustration. Each shows monthly deposits relative to a starting level of 100.

Read the first row first. The sustained raise gives the 12-month window a 20% edge. The second row shows a late jump. The shorter window still wins, by about 11%, but the edge is smaller and the history is thinner. An underwriter may ask what changed.

The third row is the trap. A single huge deposit can lift a 12-month average more than a 24-month one. That is also exactly the deposit most likely to be stripped as a one-time item. Once it is removed, the edge disappears.

Waiting can change the answer. Each month you add at the higher level pulls both averages up and strengthens the case that the raise is real. A file that looks thin at six months of higher deposits often looks solid at nine or ten.

Rising, Flat, Seasonal or Falling: Which Window?

The table below summarizes the usual lean. It is a starting point, and lender guidelines decide the final call.

Two cases deserve more thought. The first is a raise followed by a dip. Say an investor’s deposits stepped up for eight months, then eased. The 12-month number may still beat the 24-month one, but the underwriter may lean on the most recent months. Expect questions.

The second is fewer than two years of self-employment. A 12-month program may be the only route, so the window question answers itself. In that case, spend the effort on clean documentation instead.

Will an Underwriter Believe the Raise?

A raise has to be earned, repeating income to count. Lenders must verify any income they rely on with reasonably reliable third-party records, and bank statements are one such record under Regulation Z’s ability-to-repay verification rule. The Cornell Legal Information Institute’s copy of the same section is a readable reference. The rule sets the verification standard only. It says nothing about whether to use 12 or 24 months, so each lender’s program sheet fills that gap.

In practice, underwriters test a raise in four ways.

• Repetition. Several consecutive stronger months look like a new baseline. One or two look like a spike.
• Source. Deposits from new clients, a repriced service or an added contract can be explained. A single large payment from a one-off sale usually cannot.
• Cleanliness. Mixed personal and business activity makes eligible deposits harder to isolate.
• Slope. A business that is shrinking raises questions under either window.

Files with a recent step-up in deposits tend to go smoothest when the borrower labels the cause up front. A short note naming the new contract or price change, plus the matching statement pages, answers the question before it gets asked. Files that leave the underwriter guessing tend to collect a long list of explanation requests instead.

Personal vs. Business Statements

The account type interacts with the window. Business deposits take an expense factor, so the window changes the base the factor is applied to, not the factor itself.

Some programs allow an accountant-prepared expense ratio in place of the flat factor. Third-party-reviewed records are the kind the CFPB’s small-entity compliance guide treats as reliable evidence. A lender may weigh such a ratio differently from its default, so ask whether the option exists before you assume it does.

One more variable is ownership. A borrower who owns a minority share of a business may get credit for only a proportionate share of its deposits. Check how the program treats partial ownership before choosing which account to submit.

When the Window Is Not Your Choice

Many borrowers assume they can pick any window. Often the program decides. Some lender programs offer both 12 and 24 months. Some offer one. Some offer 24 months only at certain loan sizes or credit tiers. Lendmire’s role as a broker is to compare those sheets for you, not to bend them.

The loan size matters too. On larger files, an underwriter may value a longer history more than a bigger single-year number, so a 24-month option can make the file easier to read even when it yields less income.

Here are the network parameters that usually frame the choice. They are typical ranges from select lenders and are subject to lender guidelines.

• Primary residence, purchase or rate-and-term: up to 90% LTV, with stronger files earning the top of the range.
• Owner-occupied cash-out, primary or second home: up to 80% LTV with a fixed expense ratio, or 75% with an accountant-prepared ratio.
• Investment-property cash-out: around 75% LTV.
• Investment purchase on bank-statement documentation: varies by lender.
• Asset-depletion alternative on a primary residence: up to about 80% LTV.
• Loan amounts: roughly $125,000 to $3,500,000. Reserves: commonly around six months of the housing payment.

Occupancy also decides the disclosure regime. An owner-occupied file is a consumer mortgage, so TRID disclosure rules apply. A bank statement loan on a non-owner-occupied rental, including a short-term rental, is business-purpose and exempt from TRID. Say which applies to your property before you compare programs. Short-term rental rules can vary by city, county, HOA, and property type, so investors should confirm local rules before relying on projected rental income.

Term length follows each lender’s program sheet. Do not assume a long or interest-only structure is available on bank-statement documentation. Those are generally offered on the DSCR side.

Do the Two-Window Check Yourself

You can estimate both numbers before you call anyone. Follow these steps.

1. Download every statement page for the last 24 months from every account you plan to use. 2. Build a simple worksheet with one row per month. 3. Mark every deposit as earned income, transfer, refund, loan proceed, gift or one-time item. 4. Total only the earned deposits for each month. 5. Apply your ownership percentage on business accounts. 6. Average the most recent 12 months, then average all 24. 7. Compare the two, then apply a conservative expense factor to each and compare again. 8. Look at the monthly line. Is the rise steady or driven by one or two months?

If the 12-month figure beats the 24-month one by a wide margin, the raise is doing real work in your file. That is the moment to confirm the program offers the shorter window and that the rise has enough repetition behind it. If the two numbers are close, the safer, better-documented window may serve you better than the larger number.

Mistakes and Questions to Ask

Several mistakes show up repeatedly.

• Assuming more months is always safer. After a recent jump, older low months only dilute the average.
• Assuming a longer window hides a slump. Underwriters read the slope, so it does not.
• Treating the loan as undocumented. These files are fully underwritten, with deposit screening and a trend review.
• Counting every deposit. Transfers, refunds, loan proceeds and gifts come out.

On taxes, a point that confuses many self-employed borrowers: heavy deductions that shrank the return may matter less here because deposits drive the review. Tax treatment can depend on how the funds are used and how the property is held; investors should keep clear records and speak with a qualified tax professional before relying on any deduction.

Questions worth asking a broker or loan officer:

• Which windows does this program offer for my loan size and credit profile?
• Does the program use a flat expense factor, or can an accountant-prepared ratio replace it?
• Which of my deposits will be excluded?
• How many months of higher deposits does this lender want to see before it treats a raise as sustained?
• Will the lender run both windows, and which result does it use?

Where DSCR Fits Instead

A DSCR loan does not use your personal income at all. It qualifies primarily on property-level rental income covering the payment, subject to lender guidelines. A DSCR file usually asks for a short stretch of statements to show assets and reserves, not 12 or 24 months of income history. Lendmire’s complete DSCR loans guide covers how that works.

That difference changes the strategy. A bank statement loan stacks each new payment on one personal income, so an investor with several financed properties hits a ceiling set by personal debts. A DSCR loan judges property by property and can sit on an entity, subject to program terms. If rent comfortably covers the payment, DSCR sidesteps the window question. If rent is thin but your personal deposits are strong, the bank-statement route may fit better. Lendmire’s piece DSCR Loan Vs Bank Statement Loan For Investors walks through that tradeoff.

The window question also comes up on home equity lines. Lendmire’s article How to Pick 12 or 24 Months of Statements for a Bank Statement HELOC covers that product separately.

Next Steps

Lenders review every file individually, and nothing here is a commitment to lend.

About Lendmire

Lendmire is a DSCR-focused mortgage brokerage, NMLS# 2371349, placing investor loans across 41 markets, including Washington, D.C. DSCR eligibility is generally reviewed by the lender around a property’s rental income rather than personal income documentation, which fits LLC-held rentals, self-employed investors, and portfolios scaling past conventional financed-property limits. Scotsman Guide named Lendmire a Top Mortgage Workplace in both 2025 and 2026.

References

1. CFPB, Regulation Z §1026.43

2. Cornell LII, 12 CFR §1026.43

3. CFPB ATR/QM Small Entity Compliance Guide