There's a single number in real estate that quietly changes everything about how you get financed — and most people don't find out until they're already under contract. That number is five. Four units, and you're a normal homebuyer with a normal loan. Five units, and the whole game changes underneath you: different loan, different down payment, different rules, and sometimes a different person on the hook if it all goes wrong.
Nobody warns you, because the jump from a fourplex to a five-plex looks tiny — one extra front door. But that one door flips you out of residential lending and straight into commercial. Here's what actually happens the moment you cross that line, so you see it coming before it costs you a deal. And the part that surprises people isn't the down payment — it's the balloon and the recourse.
The line: 1–4 units is residential, 5+ is commercial
In the mortgage world, one to four units is residential. A fourplex — four apartments in one building — still qualifies for the same financing as a single-family house. Thirty-year fixed rate, low down payment, and here's the big one: you qualify based on your personal income — your paystubs, your tax returns, your debt-to-income ratio. And if you live in one of the units, you can even use owner-occupied programs with really low down payments.
Now add one unit. Five or more, and you're no longer a homebuyer in the eyes of the lending world. You're a commercial borrower buying a commercial property, even though it's still just apartments. Commercial financing plays by a completely different rulebook — and four specific things change.
Shift 1: DSCR — the property qualifies, not you
First, the loan doesn't qualify on your personal income anymore — it qualifies on the property's income. This is the world of DSCR, the Debt Service Coverage Ratio. The lender takes the income the building produces and divides it by the payment it has to make. They want that ratio comfortably above one — the rents more than cover the debt, usually around 1.20 to 1.25. The building has to carry itself. Your W-2 matters a lot less; the question becomes, does this property pay for itself?
Shift 2: the down payment jump
Second, the down payment. On a residential one-to-four, you might put down three-and-a-half percent, five percent, sometimes even zero on a VA loan if you're living there. Cross into commercial, and lenders usually want twenty to thirty percent down. That's potentially hundreds of thousands of dollars you didn't need one unit earlier.
Shift 3: the balloon and the term
Third, and this one really catches people — the term. A residential loan is usually a true thirty-year loan; in thirty years it's paid off. Commercial loans often don't work that way. You'll frequently see a shorter term with a balloon — the whole remaining balance comes due in, say, five, seven, or ten years. So you're paying like it's a long loan, but at year seven the bank wants the rest of the money. You have to refinance or sell before that balloon hits — and if rates are ugly or the building isn't performing that day, you get squeezed. That's the reset risk nobody mentions.
Shift 4: recourse — you personally guarantee it
Fourth is recourse. On a lot of residential loans, if everything falls apart, the lender's remedy is the house — not you personally. Commercial loans are usually recourse: you personally guarantee the debt. If the building fails and the sale doesn't cover the loan, they can come after your savings, your other property, your net worth. That's a very different level of risk than a homeowner ever signs up for.
| 1–4 units (residential) | 5+ units (commercial) | |
|---|---|---|
| Down payment | As little as 0–5% (3.5% FHA, 0% VA owner-occupied) | Usually 20–30% down |
| Term | True 30-year, fully paid off | Shorter term, often with a balloon (5/7/10 yr) |
| How you qualify | Your personal income — paystubs, tax returns, DTI | The property's income |
| DSCR | Not the driver; personal DTI rules | Building must carry itself, often 1.20–1.25 |
| Recourse | Often non-recourse — remedy is the house | Usually recourse — you personally guarantee it |
A fourplex and a five-plex sit ten feet apart, but between them runs a border. On one side you speak the language of residential lending — low down, long fixed term, your income. Step across, and everyone's suddenly speaking commercial: the building's income, a big down payment, a balloon deadline, and your personal signature on the debt. Same street, entirely different country of rules.
The bank-versus-you angle: why nobody warns you
I've been in this business since 2007 — before loan officers even needed a license — and here's the honest part: nobody's trying to scam you. The problem is that a residential loan officer often doesn't handle commercial. So when your deal crosses into five units, someone forces a square peg into a round hole, and you find out at the worst possible moment that the financing you assumed you had doesn't exist. The person selling you the fourplex-plus has every reason to keep the deal moving and none to explain that unit number five just changed your entire loan structure. So you have to be the one who knows.
Who should actually cross the line
If you've got the down payment, reserves in the bank, and a building whose rents comfortably cover the payment, five or more units can be a genuinely powerful wealth builder — you're buying a business that pays for itself. But if you're stretching to make the numbers work, or you don't have a plan for that balloon, that fifth unit can turn a dream into a trap.
Run your real numbers before anyone else does
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Educational content only — not financial, mortgage, or legal advice, and not a loan offer or solicitation. Timothy George is the founder of Infinity Financial Mortgage Corporation and has been in the mortgage business since 2007; he is not a currently-licensed loan originator and does not originate loans. Multifamily properties of five or more units are financed as commercial real estate, not residential mortgages: qualification is typically driven by the property's income through the Debt Service Coverage Ratio (DSCR), and structures, down payments, amortization, balloon terms, and recourse are non-agency and vary by lender. For the residential (1–4 unit) contrast, independent consumer information on mortgages, loan terms, and recourse is available from the Consumer Financial Protection Bureau (CFPB). Rules, ratios, and terms change over time and vary by lender — confirm the current rules and your specific situation with a currently-licensed commercial lending professional before you act.