Is Your Rental Actually Making Money?
The Landlord's Financial Model: NOI, Cap Rate & Cash-on-Cash Return
Most landlords can tell you their monthly rent. Very few can tell you their actual return. Here's how to build a real financial model for your property — and what the numbers mean.
There's a common landlord misconception that goes like this: "My mortgage is $1,200/month and I charge $1,844/month — so I'm making $644/month." That math ignores vacancy, maintenance, insurance, property taxes, management time, and capital expenditures. The actual net number is almost always significantly lower — and for some landlords, it's negative.
This guide builds the complete financial model landlords need: Net Operating Income (NOI), cap rate, and cash-on-cash return — explained in plain English with a worked example using real numbers at today's median rent of $1,844/month.
"The gap between gross rent and actual net return is where most landlord financial surprises live. The model below closes that gap — permanently."
Step 1: Gross Scheduled Income (GSI)
Start with the most you could collect if the unit were rented 100% of the time at full market rate. For a single-family rental at national median:
Step 2: Effective Gross Income (EGI) — Account for Vacancy
No property is occupied 100% of the time. National vacancy averages around 6.1%, but you should model conservatively. A single-family rental that turns over annually realistically faces 3–8% vacancy. Budget for 5% as a baseline.
Step 3: Net Operating Income (NOI) — Subtract Operating Expenses
NOI is the single most important number in rental property finance. It's what your property generates before debt service (your mortgage) and taxes. Here are the operating expense categories every landlord must include:
A commonly cited rule of thumb in rental investing: operating expenses (excluding mortgage) typically consume 40–55% of gross rent over time. On $22,128 gross, that's $8,851–$12,170 in expenses — consistent with the model above. If your expense estimate comes in well below 40% of gross rent, you're probably missing cost categories.
Step 4: Cap Rate — What Your Property Is Worth as a Business
Cap rate (capitalization rate) measures what return the property generates as a business independent of how you financed it. It lets you compare your rental to other investments and other properties objectively.
CBRE's current national average cap rate for single-family rentals is approximately 5.8%. Properties in coastal metros (Los Angeles, Seattle, New York) routinely trade at 2–4% cap rates — meaning the income yield is low and investors are primarily buying for appreciation. Properties in the Midwest, Southeast, and secondary markets often show 6–9% cap rates.
A low cap rate isn't necessarily bad — but you need to know what you're buying. A 2.8% cap rate property in San Francisco may compound wealth through appreciation even if cash flow is minimal. A 7% cap rate property in a declining market may generate cash flow while losing value. Cap rate is one metric; it doesn't tell the whole story by itself.
Step 5: Cash-on-Cash Return — What Your Down Payment Actually Earns
Cash-on-cash (CoC) return is the most relevant metric for most landlords. It measures what your actual cash investment — the down payment and closing costs — earns each year after paying the mortgage.
That negative cash-on-cash return is exactly why so many landlords who purchased at today's median price point are not actually cash-flowing — the mortgage cost overwhelms the NOI at 6.11% rates and current price levels.
What makes a property cash-flow positive?
This isn't unique to today — it's the fundamental tension in residential rental investing. Run the same model with different inputs to see what changes it:
| Scenario | Annual NOI | Annual P&I | Annual Cash Flow | CoC Return |
|---|---|---|---|---|
| Current (6.11%, $320K, $1,844 rent) | $8,900 | $18,624 | ($9,724) | -13.5% |
| Lower rate (3%, same property — 2021) | $8,900 | $12,965 | ($4,065) | -5.6% |
| Higher rent (+20%, $2,213/mo) | $12,400 | $18,624 | ($6,224) | -8.6% |
| Smaller loan (40% down, lower P&I) | $8,900 | $14,000 | ($5,100) | -4.7% |
| Midwest high-yield ($180K property, $1,400 rent) | $7,200 | $10,284 | ($3,084) | -8.4% |
| Paid-off property (no mortgage) | $8,900 | $0 | $8,900 | +12.4% |
The cash-on-cash analysis above makes many rentals look like losing investments. But it misses two major return components: equity paydown (the mortgage principal your tenant pays down each month) and property appreciation. At $320K with a 1% annual appreciation rate, you're building $3,200/year in equity plus ~$3,500/year in principal paydown. Add those back and the total return picture changes substantially — even in a negative cash-flow property.
Your Full Return Stack
The complete return picture for a rental property has four components. Most landlords only track one.
- Cash flow. The after-mortgage, after-expense surplus (or deficit) each month.
- Principal paydown. The portion of each mortgage payment that builds equity. On a $256K loan at 6.11%, year-one principal paydown is approximately $3,400.
- Appreciation. Home values nationally have grown ~3.5% per year on average over the past 20 years. On a $320K property that's $11,200/year — though this is realized only at sale.
- Tax benefits. Depreciation (you can deduct 1/27.5th of the property value each year), mortgage interest deduction, and all operating expenses reduce your taxable income. These can create "paper losses" that offset other income for many landlords.
The Bottom Line
Most landlords at today's price levels are not cash-flowing on a financed property — and that's okay if you understand the full return picture and your situation. What matters is that you model it honestly, know your actual numbers, and don't make decisions based on gross rent alone.
Build this model for your own property. Plug in your actual rent, your actual expenses, and your actual mortgage — then compare your NOI, cap rate, and cash-on-cash return to the benchmarks above. The answers may surprise you.