Expense Factor Vs CPA Letter For A K-1 Practice Owner Mortgage — The Quick Read: An expense factor is a flat percentage a lender subtracts from your business deposits before counting income — it assumes your costs, it doesn’t measure them. A CPA letter replaces that assumption with a lower, documented number your accountant will actually put their name on. For a K-1 partner, the right choice depends on whether your practice distributes cash regularly, how much you own, and whether your real overhead runs below what the lender’s default assumes.
Neither tool is better in the abstract. They solve different problems for different borrowers, and picking wrong costs qualifying income you didn’t have to lose.
Key Terms Defined
Expense factor — a fixed percentage a lender deducts from gross business deposits to estimate your real take-home income, used as a placeholder when there’s no third-party documentation of actual costs.
CPA letter — a written statement from a certified accountant confirming specific factual details about your business, such as your actual expense ratio, ownership stake, or how long the practice has operated.
K-1 — the tax form a partnership or S-corp issues to an owner showing their share of the entity’s income, whether or not that income was actually paid out in cash.
DSCR loan — a business-purpose mortgage that is reviewed on a rental property’s own cash flow instead of the borrower’s personal income, traditional personal-income documentation, or K-1s.
Ownership percentage — the share of a business entity a borrower holds, which determines how much of that entity’s deposits or K-1 income a lender will count toward qualification.
What an Expense Factor Actually Does
An expense factor isn’t a real measurement. It’s a lender’s conservative guess about your overhead. Lenders apply it before any of your business deposits count as income. Across the wholesale programs Lendmire places files with, expense-factor defaults typically scale with staffing and business type. They run lowest for a service business with no employees. They run higher for businesses with more staff or those selling a physical product.
Here’s the mechanic in plain terms. The lender totals eligible deposits over 12 or 24 consecutive statement months, multiplies by your ownership percentage, then applies the expense factor to knock the number down before it counts as qualifying income. A practice with substantial monthly deposits landing in the business account at a 50% factor gets treated as if only half of that is real, spendable income, and that reduction happens before anything is prorated by ownership stake.
The factor doesn’t care that your actual overhead is lower. It’s a category assumption, not a personalized one. That’s exactly the gap a CPA letter is built to close — complete DSCR loans guide breaks down how documentation choices affect qualifying income across non-QM programs more broadly.
What a CPA Letter Can — and Can’t — Say
A CPA letter can confirm facts your accountant can support with actual records: your real expense ratio, your ownership percentage, how long the practice has operated. It cannot promise you’ll be approved, and it cannot function as an audit-level guarantee — the accountant is stating what the books show, not underwriting the loan.
This matters because the professional body governing CPA conduct has drawn a hard line here. AICPA & CIMA’s guidance on comfort letters flags real liability exposure for accountants asked to sign broad assurance letters. A CPA who implies more certainty than their engagement supports can run into professional-standards trouble. That’s why a good mortgage-savvy CPA writes a narrow, factual letter. A CPA unfamiliar with lending sometimes writes something vague instead, and an underwriter kicks it back.
The letter typically needs to state the time period reviewed, the methodology used to calculate the expense ratio, the percentage itself, and confirmation the accountant reviewed records supporting it. Loose language — “the business appears healthy” or “income should continue” — isn’t underwriting fuel. It’s the kind of statement AICPA guidance specifically warns accountants against putting their name on unless they’ve done a formal engagement to back it up.
Side-by-Side
| Factor | Expense Factor | CPA Letter |
|---|---|---|
| Review basis | Flat percentage by business type | Documented actual expense ratio |
| Documentation needed | Bank statements only | Bank statements + signed CPA letter |
| Best for | Businesses with typical/higher overhead | Low-overhead practices below the default |
| Who provides it | Built into the loan program | Third-party CPA or tax preparer |
| Entity fit | Sole props, LLCs, S-corps, C-corps | Same entities, when actual costs run lower |
| Timeline described | Standard bank-statement file review | Adds a step — letter must be requested and reviewed |
| Reserve expectations | Set by loan size, not documentation choice | Same — documentation path doesn’t change reserves |
When the Expense Factor Is the Better Fit
The flat default works best when your actual overhead is close to — or above — what the program already assumes, or when getting a CPA letter isn’t worth the extra step. If your practice runs real staff, real equipment, and real supply costs, fighting for a lower number your accountant can’t actually support wastes time and risks a letter that gets rejected anyway.
It also fits practices with commingled or inconsistent account routing, where an accountant would struggle to isolate a clean, defensible expense ratio in the first place. A dental practice with a full clinical staff, or a medical group with real overhead running close to industry norms, often lands close to the standard factor regardless of what a letter says. In those cases, the flat assumption isn’t really costing you anything — pushing for a documented override just adds a step without moving the number.
The default also makes sense for K-1 partners whose distributions are irregular or hard to trace to a specific ownership share. If deposits don’t cleanly map to your percentage of the entity, an underwriter may lean on the simpler flat-factor path rather than untangling a CPA letter that tries to allocate shared account activity.
When the CPA Letter Is the Better Fit
The letter earns its keep when your actual costs run meaningfully below the program default. This applies to a solo consultant, an attorney running a lean practice, or a single-owner professional-services entity where real overhead sits well under the flat assumption. If your true expense ratio is documented at a lower percentage than the default, that difference flows straight into qualifying income.
It’s also the stronger path for K-1 partners whose ordinary business income on the K-1 doesn’t match what actually hits their personal account. A partner showing solid K-1 income but modest draws has a documentation mismatch a flat bank-statement factor can’t fix — the deposits simply won’t reflect the income the K-1 reports. In that scenario, a properly scoped CPA letter, or a shift toward a profit-and-loss qualification path, often does more for the file than any adjustment to the expense factor.
Ownership proration matters here too. Take a minority partner — someone below a meaningful ownership threshold. Bureau of Labor Statistics data shows self-employed workers made up 5.7% of the nonagricultural workforce in the most recent tracked quarter. A meaningful share of those workers are structured through partnerships and S-corps. Often, this minority partner can’t count a shared business account’s deposits at all, unless documentation clarifies their stake. A CPA letter that plainly states ownership percentage and the borrower’s access to funds can make the difference between an account counting and not counting.
Practice owners specifically tend to fall into this camp. Across files Lendmire’s team sees, the practitioners with the cleanest cases for a CPA letter are the ones whose traditional personal-income documentation understate real cash flow because of legitimate deductions — equipment, home office, retirement contributions — that don’t reflect what actually lands in their pocket. The IRS’s own instructions for Schedule K-1 confirm the structural root of this mismatch: a partner is taxed on their allocated share of partnership income whether or not that income was actually distributed to them. That gap between what the K-1 reports and what actually hit an account is precisely the problem a well-scoped letter is built to solve.
A Worked Scenario
Picture a K-1 partner who owns a real stake in a professional-services partnership. Business deposits flow through a dedicated business account. Suppose the file qualifies under the standard flat factor for a small-staff service business. In that case, qualifying income equals whatever percentage of deposits the default keeps, after adjusting for ownership share.
Now run the same deposits with a CPA letter that documents a lower, defensible expense ratio specific to that practice’s actual costs. More of each dollar counts as income instead of assumed overhead. So the qualifying income figure rises. Sometimes it rises enough to move the file into a stronger leverage tier, or to clear a debt-to-income threshold that was tight under the default assumption.
The gap between the two outcomes isn’t cosmetic. On a leaner practice, the swing between a default factor and a documented lower ratio can be the difference between qualifying at a program’s standard tier and needing a smaller loan amount, or between clearing reserves comfortably and coming up short. This is exactly why the choice deserves attention before the file goes to underwriting, not after.
Where DSCR Changes the Whole Question
For a rental-property purchase, this entire debate can become irrelevant. A DSCR loan is reviewed primarily on the property’s own rental income covering the payment, subject to lender guidelines — not on the borrower’s K-1, traditional personal-income documentation, or bank-statement expense math at all. Programs across Lendmire’s wholesale network size these loans from $300,000 to $30,000,000, with leverage stepping down as loan size climbs and every file above roughly $4,000,000 reviewed case by case before submission.
That structural separation matters for a practice owner juggling both a primary residence purchase and a rental portfolio. The personal file — where expense factor versus CPA letter genuinely matters — is evaluated on its own. Each rental acquisition stands on its own property-level cash flow, independent of how the practice’s K-1 income gets documented. A borrower whose personal file is squeezed by a conservative expense factor doesn’t need that fight to spill into the investment side of the ledger.
That said, documentation choices on the personal side can still affect a DSCR file. This happens when a lender adds reserve requirements or down-payment sourcing rules tied to overall borrower liquidity. Across the network Lendmire works with, reserve expectations on larger files typically start at three months of payments up to a certain loan size. They step up to six months, then nine months, as the loan amount grows. Those reserves have to come from somewhere. That’s where a stronger personal-income picture from a well-placed CPA letter can help.
Common Mistakes Practice Owners Make
The biggest one is assuming any CPA letter automatically lowers the number. It doesn’t — a generic assurance letter that doesn’t state a specific methodology and time period often gets rejected outright, leaving the file to fall back on the flat default anyway.
The second is waiting until underwriting flags the issue instead of deciding upfront. A practice owner who knows their actual overhead runs well below the standard factor should have that conversation with their accountant before submitting the file, not after a preliminary approval comes back lower than expected.
The third is not accounting for ownership percentage. K-1 partners sometimes assume 100% of business deposits will count toward their income, when in fact the lender prorates by ownership stake first — a 50% owner sees half the deposit-derived income, regardless of which documentation path is used.
FAQ
Does a CPA letter guarantee a lower expense factor?
No. A CPA letter documents actual costs, but the underwriter still reviews the letter alongside deposit history, ownership documentation, and consistency across statements. A well-scoped letter can move the number; it doesn’t override underwriting.
Can I request a specific expense factor from my lender?
No. The lender sets the default factor by business type. Only a third-party CPA, tax preparer, or bookkeeping professional can support a lower, documented figure to replace it.
My K-1 shows strong income but my draws are small — what happens?
This is a common mismatch for K-1 partners in partnerships that retain earnings rather than distribute them. In that scenario, a profit-and-loss qualification path or a CPA letter explaining the retained-earnings structure often works better than trying to force the flat expense-factor formula onto thin deposit activity.
Does my ownership percentage change which documentation path I should use?
Yes. Lenders generally require documented ownership before counting a shared business account’s deposits at all. A minority partner without clear access to the operating account may need a CPA letter just to establish that the income is attributable to them in the first place.
Do I need a CPA letter if I’m buying a rental property instead of a primary residence?
Usually not. A DSCR loan is reviewed primarily on the property’s rental income covering the payment, subject to lender guidelines, so personal K-1 documentation typically isn’t part of that calculation at all — see DSCR loan vs owner-occupied mortgage for how the two qualification paths diverge.
DSCR loans are business-purpose loans for non-owner-occupied investment properties. Because they’re underwritten as investor loans rather than owner-occupied mortgages, they’re reviewed under different rules than the personal-income documentation discussed above.
Tax treatment can depend on how funds are used and how a property is held; practice owners should keep clear records and speak with a qualified tax professional before relying on any deduction or income characterization.
If you’re a practice owner weighing which documentation path fits your file — or wondering whether your rental acquisitions should sidestep this question entirely through a DSCR structure — Lendmire can help you compare options based on your income documentation, credit profile, leverage, and property goals. Reach the team at 828-256-2183 or request a quote to walk through your specific K-1 structure.
For current guidelines and terms, see Lendmire’s super jumbo bank statement loan programs page.
Self-employed borrowers can compare both super jumbo programs on Lendmire’s self-employed mortgages page.
About Lendmire
Lendmire (NMLS# 2371349), a non-QM mortgage broker serving investors in 40 markets including Washington, D.C., helps structure DSCR scenarios commonly evaluated around a property’s rental income rather than personal income paperwork, subject to lender guidelines. A Scotsman Guide Top Mortgage Workplace in 2025 and 2026, Lendmire places loans through wholesale investor lenders and is not a direct lender.
Lendmire’s Top Mortgage Workplace recognition is documented by Scotsman Guide 2025 Top Mortgage Workplace and Scotsman Guide 2026 Top Mortgage Workplace.
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References
1. AICPA & CIMA – CPA comfort letter guidance
2. Bureau of Labor Statistics – Nonagricultural self-employment rate Q4 2023
3. IRS – Partner’s Instructions for Schedule K-1 (Form 1065), 2025
This article is part of Lendmire’s super jumbo bank statement loan program — full qualification details, guidelines, and scenarios live on the program page.
Related reading: Expense Factor Vs CPA Letter On A Bank Statement Loan For A 1099 Earner · Does The Expense Factor Replace A CPA Letter On A Bank Statement Loan? · Expense Factor Vs CPA Letter On A Bank Statement Loan
Brandon Miller
Founder & CEO, Mortgage Loan Originator, Lendmire LLC
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Compliance and disclosures. Lendmire (NMLS# 2371349) is a licensed mortgage broker and is not a direct lender, depository institution, financial advisor, or tax professional. Content in this article is general market analysis and educational information — not financial, legal, or tax advice for any specific situation. Lendmire does not guarantee loan approval; every transaction is subject to underwriting by the funding lender. Mortgage pricing and loan program guidelines are subject to change at any time without notice and vary by borrower characteristics, property type, and state regulations. Lendmire complies with Equal Housing Opportunity. Licensure verification: NMLS Consumer Access.