12 vs. 24 Month Bank Statements When Deposits Jumped or Dropped This Year

The Quick Read: Use the 12-month window when your deposits rose and older, leaner months would only drag the average down. Use the 24-month window when income is seasonal, lumpy, or slipped after a stronger year. Run both numbers either way, because the underwriter reads the trend, not just the average. Neither window is better in general. Each one answers a different question about your income.

• A jump in deposits usually favors 12 months, because the older, weaker year drops out of the average.
• A drop usually favors 24 months, because the stronger prior year softens the average. It does not hide the direction of the trend.
• One-time deposits, transfers between your own accounts, and loan proceeds are typically stripped out of either window.
• A short written explanation of why deposits changed helps in both directions.

The Honest Answer on Who Each Window Is For

The 12-month window is for the borrower whose business is growing. It shows the most recent year and nothing older. The 24-month window is for the borrower whose income swings, runs in seasons, or fell after a strong stretch. It shows the full cycle.

Neither choice is a trick. Both are consecutive-month deposit reviews, and the program sets which window is allowed. Across the network of select wholesale lenders Lendmire works with, 12 months of statements is the baseline documentation. Whether a lender will also average 24 months depends on the lender’s program sheet and on your file.

The practical move is to run both averages before you apply. Take the stronger result, then ask whether you can explain the gap between the two.

Side-by-Side

This table describes how the two windows typically behave on bank-statement files. Exact treatment depends on each lender’s guidelines.

Two things stay the same in both columns. Business accounts get an expense factor and an ownership-percentage adjustment, and personal accounts are generally counted closer to face value. The window changes how many months go into the average. It does not change the method.

How Deposits Become Qualifying Income

A bank-statement lender turns deposits into income in a few plain steps. The steps are the same whichever window you use.

1. You supply every page of every account used, whether personal, business, or both.

2. The underwriter screens out deposits that are not income. Transfers between your own accounts, loan proceeds, gifts, one-time windfalls such as an asset sale, and unsourced cash are typically excluded.

3. Business-account deposits get an expense factor, which accounts for the cost of running the business. The factor varies by lender. A CPA letter or profit-and-loss statement may support a different factor where the program allows it.

4. The remaining total is divided by the number of months in the window.

5. The underwriter compares that figure against the proposed payment and the rest of your obligations.

Notice the order. The window only matters at step four. Everything before it is about deposit quality, and a messy deposit history will hurt you in either window.

Worked Example With Made-Up Index Numbers

Here is a hypothetical borrower, with income shown as an index so no dollar amounts are implied. These are modeled assumptions, not market data. Say the prior year of eligible deposits averages 100 points a month.

In the jump row, the 12-month window gives the higher figure. The older, leaner year pulls the 24-month number down by roughly 12% from the 12-month result. In the drop row, the 24-month figure comes out about 21% higher than the 12-month figure.

That second row needs a caution. The 24-month average looks better, but the underwriter can still see that the recent year came in lower. A steep decline draws questions even when the average clears. Averaging softens the number. It does not remove the trend from the file.

When 12 Months Is the Better Fit

The 12-month window is the stronger choice when your recent deposits are meaningfully higher than your prior year and you can show why. A growing business is the classic case. Say you landed two large contracts, added a second location, or finished a slow ramp-up year. Twelve months lets your current earning power carry the file instead of a number that includes the ramp-up.

It also fits when the prior year was unusually weak for a reason that has ended. Perhaps you spent months recovering from an illness, a business relocation, or a deliberate scale-back. Dropping that year out is reasonable when the explanation is clear and documented.

A few cautions apply.

• Seasonal income. If your 12 months happen to include only the high season, the average can overstate what you earn across a full cycle. Underwriters notice this.
• One-time deposits. A large lump-sum deposit moves a 12-month average more than a 24-month one. If it is not stripped out, expect questions. If it is stripped out, it adds nothing.
• Short history. A year of strong deposits after a thin start can raise questions about durability. A short letter and proof of ongoing contracts or clients help.

Twelve months is also less paperwork. For many self-employed borrowers, that matters, since gathering statements across several accounts takes real effort.

When 24 Months Is the Better Fit

The 24-month window is the stronger choice when your income is uneven by nature, or when the most recent year fell after a better one. Contractors, agents, seasonal businesses, and anyone paid in large irregular chunks tend to look steadier across two years than across one. The longer average captures the full cycle, highs and lows included.

It also helps after a down year with a clear cause. Say a major client left, then you replaced the client, but only part of the year reflects the recovery. The two-year average gives credit for the stronger period while the file still shows the dip.

Some lenders and loan sizes also lean toward the longer view because it signals durability. That is a lender-level preference, not a universal rule, and the network’s program sheets differ on it.

Know what 24 months will not do.

• It will not hide a decline. Underwriters read both the average and the slope, and a steep recent drop may carry more weight than an older one.
• It will not help a sustained jump. The older year dilutes your best number.
• It means more documentation. Two years of statements across every account used, with every page included.

For a deeper look at how a falling-income file gets read, see Lendmire’s coverage of 12 vs 24 month bank statements when income declined.

What Underwriters Read Beyond the Average

Most reviewers look at three things beyond the arithmetic. Know them before you submit.

Deposit quality. Underwriters want consistent sources, few overdrafts or returned items, and ownership that matches the account. A deposit that cannot be sourced is usually excluded. Large deposits trigger documentation requests, not automatic denial.

The reason for any step change. A lost client, a planned scale-back, a prior-year windfall, or money moving between accounts all produce different readings. Write the reason down in plain words and attach proof where you have it. A letter that says what happened and what changed since is more useful than a long essay.

The direction of the trend. An older dip that has recovered reads differently from a dip that is still going. If you applied this month, the underwriter sees your latest statement, and that statement matters.

Here is a point of honest judgment. If your deposits just dropped and a recovery is clearly underway, waiting a month or two can sometimes help more than applying now. If the drop is permanent, waiting does nothing, and a different path may fit better. A broker looking at your numbers can usually tell which situation you are in.

Where Occupancy and Property Type Change the Picture

Everything above assumes you are qualifying on income. Whether that applies depends on what you are buying and how you will use it.

Bank-statement files differ by occupancy. On a primary residence, select lenders in the network go up to 90% LTV on a purchase or rate-and-term refinance, with the strongest files earning the top of that range. On an owner-occupied cash-out refinance of a primary residence or second home, the ceiling is up to 80% LTV with a fixed expense ratio, or 75% with an accountant-prepared ratio, depending on loan size and credit. On an investment property cash-out, leverage tops out around 75% LTV. Investment purchases on bank-statement documentation vary by lender, so that number is better discussed file by file. Loan amounts typically run from $125,000 to $3,500,000, subject to lender guidelines.

Occupancy also decides the disclosure regime. A loan on a home you will live in, including a second home, is a consumer mortgage, and consumer disclosure rules apply. A loan on a non-owner-occupied rental, including a short-term rental, is business-purpose and exempt from those disclosure rules. Because they are business-purpose investor loans, they are reviewed differently from a standard owner-occupied mortgage. The federal ability-to-repay rule assessment says that rule does not apply to credit extended primarily for a business purpose, even when a dwelling secures it. Business purpose is not a free pass, though. A law-firm analysis from Hunton cautions that miscategorizing a loan carries penalties and assignee exposure, so lenders still run their own diligence.

The practical result is that no federal rule sets a 12-month or 24-month lookback. The window is a lender credit-policy choice, which is why your best number depends on the program.

If you are buying a rental that will carry itself, there is another lane. A DSCR loan is reviewed primarily on property-level rental income covering the payment, subject to lender guidelines, so your own deposits are not averaged into income. Personal statements still verify down payment, closing costs, and reserves, and large recent deposits may need sourcing. Lendmire’s complete DSCR loans guide covers that path. A borrower buying a home to live in needs the income lane, which is where the 12-versus-24 question lives.

One more point on ownership. Whether a program accepts an LLC as the borrower on bank-statement income depends on program guidelines, so raise it early if you plan to hold title in an entity.

Pre-Application Checklist

Do these before you submit anything.

• Compute both averages from eligible deposits only, after removing transfers, loan proceeds, and one-time items.
• Flag every deposit that looks unusual and gather the paperwork that explains it.
• Decide whether your recent change is a lasting jump, a one-off spike, a seasonal dip, or an ongoing decline.
• Write a short explanation of any step change, with supporting documents where you have them.
• Collect separate asset and reserve statements, since reserves commonly run around 6 months of the housing payment.
• Ask whether waiting a month or two would change the story in your favor.

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.

Key Terms Defined

Expense factor: the share of business deposits the lender assumes goes to operating costs, so only the remainder counts as income.

Non-QM: a loan that does not follow standard government-backed documentation rules, such as one that is reviewed on bank statements instead of tax returns and pay stubs.

LTV (loan-to-value): the loan amount divided by the property value, shown as a percentage.

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

The Balanced Verdict

Pick 12 months when your income is climbing and you can explain the climb. Pick 24 months when your income is seasonal, lumpy, or fell after a stronger stretch. When income is flat, the choice barely matters, so use whichever window is less paperwork.

Three habits matter more than the window. Run both numbers. Keep your deposits clean. Explain every change in writing. A borrower who does those three things usually has a stronger file than one who simply picks the bigger figure.

Next Step

Lendmire is a mortgage broker that arranges financing through select lenders in its wholesale network, and the owner-occupied consumer programs described here are available in 16 states. Reach the team at 828-256-2183 or request a quote. Every file is underwritten individually, and nothing here is a commitment to lend.

For current guidelines and terms, see Lendmire’s bank statement loan programs page.

About Lendmire

A non-QM mortgage broker (NMLS# 2371349), Lendmire arranges DSCR financing for real estate investors in 41 markets — 40 states plus Washington, D.C. Because deals are underwritten primarily on property cash flow rather than personal income documentation, the structure suits self-employed buyers and entity-owned portfolios. Lendmire places loans through wholesale investor lenders; it is not a direct lender. Scotsman Guide named Lendmire a Top Mortgage Workplace in both 2025 and 2026.

References

1. CFPB: CFPB Ability to Repay Qualified Mortgage Assessment Report

2. Hunton: Beware of Business Purpose