Small multifamily — duplexes, triplexes, and fourplexes — is the most underrated asset class in DSCR lending. The same capital that buys one single-family rental can control two to four income streams, vacancy risk is diversified across units, and per-door acquisition costs typically run 20–35 percent below comparable single-family pricing in the same submarket. Yet most DSCR borrowers default to single-family because that's where their experience is, and most never learn how lenders actually treat 2–4 unit files differently.
The DSCR math advantage
Start with a representative comparison in a mid-priced Midwest metro. A single-family rental at $220,000 purchase, 80 percent LTV, $176,000 loan at 8.0 percent: principal and interest is $1,291, taxes and insurance add roughly $370, total PITIA of $1,661. Market rent at $1,850 produces a DSCR of 1.11.
Now a fourplex in the same submarket at $440,000 — twice the capital, but four doors. At 75 percent LTV (more on the leverage haircut below), the $330,000 loan at 8.25 percent carries P&I of $2,479. Taxes and insurance on small multifamily run heavier, call it $720 monthly. Total PITIA: $3,199. Four units renting at $1,050 each is $4,200 gross. DSCR = 4,200 / 3,199 = 1.31.
That 20-point spread over the single-family deal isn't an artifact of this example — it's structural. Per-unit acquisition cost on the fourplex is $110,000 against $220,000 for the single-family, while per-unit rent only drops from $1,850 to $1,050. Rent doesn't scale down as fast as price does. That asymmetry is the entire small-multifamily thesis, and DSCR underwriting captures it directly because the ratio is the qualification.
Where lenders haircut 2–4 unit deals
The trade-off is leverage and pricing. Nearly every DSCR lender applies a 5-point LTV reduction on 2–4 unit properties relative to single-family. Where SFR purchase money tops out at 80 percent LTV, expect 75 percent on a duplex through fourplex. Cash-out refinances follow the same pattern: 75 percent max on SFR becomes 70 percent on small multifamily at most shops.
Rate adjustments run 25–50 basis points above the single-family grid for the same DSCR, LTV, and credit profile. A borrower pricing at 7.875 percent on an SFR file should expect 8.125–8.375 percent on a fourplex with otherwise identical characteristics. Some top-tier lenders compress this to 12.5–25 basis points for DSCR above 1.25 — worth shopping, because the spread between lenders on 2–4 unit pricing is wider than on single-family.
Minimum DSCR requirements are usually unchanged at 1.0–1.10, but reserve requirements step up: where 3–6 months of PITIA is standard for SFR, many lenders want 6 months minimum on 2–4 unit files, and 9–12 months for borrowers with limited landlord history.
Appraisal mechanics: the 1025 and the rent schedule
Single-family DSCR appraisals use the 1004 form with a 1007 rent schedule. Small multifamily uses the 1025 (Small Residential Income Property Appraisal Report), which includes a unit-by-unit market rent analysis built in. Two practical consequences follow.
First, the appraiser opines on market rent for each unit individually. If the property has a mix — say a 3-bed unit and three 2-bed units — each gets its own comparable rent analysis. Below-market in-place leases don't necessarily hurt you: most DSCR lenders qualify off the lower of in-place lease or market rent per unit, but several top-tier shops use market rent when units are vacant or on month-to-month terms. Ask before you apply; on a four-unit property the difference between in-place and market across all units can swing DSCR by 10–20 points.
Second, the 1025 includes an income approach to value, and on 2–4 unit properties appraisers weight it more heavily than on SFR. A fourplex with strong rents in a weak comp environment can appraise better than the sales comps alone would suggest — and the reverse is true in markets where small multifamily trades at low cap rates relative to rents.
Vacant units and lease-up risk
A common stumbling block: buying a 2–4 unit property with one or more vacant units. Lender treatment varies meaningfully. The most flexible shops use 100 percent of market rent from the 1025 for vacant units on purchase transactions. Mid-spectrum lenders apply a vacancy haircut, counting 75–90 percent of market rent on unoccupied units. The strictest require all units leased before closing, or price the file as if vacant units produce zero income — which kills most deals.
On refinances the standards tighten further. Most lenders want occupied units with executed leases, and several apply seasoning: 30–90 days of in-place tenancy before the rent counts. If you're executing a BRRRR on a fourplex, sequence your lease-up so units are occupied before the appraisal is ordered, not after.
House hacking is off the table — and that's fine
Owner-occupied 2–4 unit purchases (house hacking) are conventional and FHA territory; DSCR loans are business-purpose by definition and require non-owner occupancy, typically certified at closing. Where this matters: investors who previously house-hacked a duplex with FHA financing and have since moved out can refinance into a DSCR loan, vest in an LLC, and free their conventional and FHA eligibility for the next personal residence. That refi path — FHA out, DSCR in — is one of the cleaner portfolio-scaling moves available to early-stage investors, and the DSCR cash-out at 70 percent LTV often recovers most of the original down payment after a few years of appreciation.
Five-plus units is a different product
The 2–4 unit boundary is not arbitrary — it's the residential/commercial line. Five units and above moves to commercial DSCR or small-balance commercial loans: different docs, recourse and non-recourse structures, 20–25 year amortizations instead of 30, and frequently interest-rate floors and yield maintenance prepay structures. If you're evaluating a 5-unit against a fourplex, the fourplex usually wins on financing alone: 30-year fixed amortization, 75 percent LTV, and standard 3-2-1 or 5-4-3-2-1 prepay penalty structures rather than yield maintenance. Some investors deliberately seek out fourplexes adjacent to 5–8 unit buildings precisely because the residential financing is cheaper and easier to refinance.
What actually gets 2–4 unit files declined
The decline patterns are predictable. Non-conforming unit counts — a "fourplex" with a fifth unauthorized unit in the basement — will be flagged by the appraiser and either kill the deal or force the file to a commercial product. Mixed-use contamination — a storefront with three apartments above — is outside residential DSCR guidelines at nearly all lenders regardless of how residential the income mix looks. Condition issues compound across units: a C5 condition rating on any single unit can drag the whole property rating down.
And the boring one: insurance. Small multifamily hazard premiums have climbed 30–60 percent since 2023 in coastal and hail-belt states. A fourplex in Tampa or Oklahoma City can carry $6,000–$10,000 annual premiums, which is $500–$830 a month of PITIA. Run insurance quotes before going under contract — on thin deals, the premium alone moves DSCR by 15–25 points and is the most common reason a 1.20 DSCR estimate funds as a 1.02.
The bottom line
For investors optimizing cash flow per dollar of capital deployed, 2–4 unit properties financed with DSCR loans are hard to beat: better ratios, diversified vacancy risk, and per-door costs that single-family can't match. Price the leverage haircut (75 percent LTV), the rate adjustment (25–50 basis points), and the heavier insurance load into your offer — and confirm the lender's vacant-unit and lease-seasoning policy before you apply, because that's where small-multifamily files most often surprise borrowers at the margin.