You found a duplex listed at $350,000. Each unit rents for $1,400/month, for a total of $2,800/month in gross rent. That looks like a 9.6% gross yield. But your actual monthly cash flow after expenses — the money deposited in your checking account — will be substantially lower. Here is the complete breakdown.
Gross vs. Net Yield: Why the Difference Matters
Gross yield is annual rent divided by purchase price. On this duplex: $33,600 / $350,000 = 9.6%. Gross yield is a useful screening number to quickly compare properties, but it ignores every expense between collecting rent and paying your mortgage.
Net yield (or net rental yield) subtracts all operating expenses before dividing by property price. This is what you actually earn on the asset — and it is typically 3-5 percentage points lower than gross yield.
The Real Expense Line Items
Here is a realistic monthly expense breakdown for this $350,000 duplex with a 25% down payment ($87,500 down):
| Expense | Monthly Amount | Notes |
|---|---|---|
| Mortgage P&I (6.5%, 30yr, $262,500 loan) | $1,659 | Principal and interest only |
| Property taxes | $365 | 1.25% annual rate / 12 |
| Landlord insurance | $120 | ~0.4% of property value / 12 |
| Maintenance & repairs | $280 | ~1% of value annually / 12 |
| Vacancy allowance | $140 | 5% of gross rent ($2,800 x 5%) |
| Property management | $280 | 10% of collected rent (if used) |
| Capital expenditure reserve | $140 | Roof, HVAC, appliances fund |
| Total expenses | $2,984 |
Monthly cash flow: $2,800 - $2,984 = -$184
This duplex generates negative cash flow at current purchase price and interest rates. Before adjusting anything, this deal does not work as-is.
The 50% Rule: A Fast Screening Heuristic
Real estate investors use the 50% rule as a quick filter: assume that 50% of gross rent will be consumed by operating expenses (excluding the mortgage). That means $1,400 per month goes to expenses and $1,400 services debt. On a $262,500 mortgage at 6.5%, the payment is $1,659 — $259 more than what the rule leaves for debt service.
The 50% rule signals that this property, at this price and rate, fails the quick math test. The rule is approximate — in good condition with low property taxes, operating expenses might be 40-45% of rent. In older buildings or high-tax jurisdictions, they run 55-60%.
Cash-on-Cash Return With 25% Down
Cash-on-cash return measures your annual pre-tax cash flow divided by the actual cash you invested. It is the metric that tells you how hard your down payment is working.
- Total cash invested: $87,500 down + $8,000 closing costs = $95,500
- Annual cash flow: -$184/month x 12 = -$2,208
- Cash-on-cash return: -$2,208 / $95,500 = -2.3%
This deal destroys cash at the stated price. For a minimum acceptable return, most investors target 6-10% cash-on-cash. To hit 6% CoC on $95,500 invested, you need annual pre-tax cash flow of $5,730 — about $478/month positive cash flow. That requires either a lower purchase price, higher rents, or significantly lower expenses.
What Would Make This Deal Work
Lower purchase price. If you negotiate the price to $310,000 with $77,500 down, the mortgage drops to $1,463/month. Total expenses fall to roughly $2,778, and monthly cash flow turns positive at around +$22/month. Still thin, but CoC improves as the loan balance decreases.
Higher rents. If each unit can command $1,600/month (total $3,200), the same expense stack produces +$216/month positive cash flow and a 2.7% CoC. Better — but still below the 6-8% threshold many investors require.
Lower down payment + house hacking. If you live in one unit and rent the other at $1,400, your housing cost is the mortgage minus rent received. On $262,500 at 6.5%, your mortgage is $1,659 minus $1,400 = $259/month net cost. As an owner-occupant, you also qualify for a conventional loan with 5-10% down instead of 25%.
Net Operating Income and Cap Rate
Remove the mortgage from the expense calculation to get the asset's standalone performance metric:
- Gross rent: $2,800/month = $33,600/year
- Operating expenses (excl. mortgage): $1,325/month = $15,900/year
- Net operating income (NOI): $17,700/year
- Cap rate: $17,700 / $350,000 = 5.1%
A 5.1% cap rate is below the 6-8% most investors require for a residential rental in a secondary market. In a high-demand metro where appreciation is the primary return driver, 5% cap rates are common and accepted. In a flat market, this number should make you pause.
Gross Rent Multiplier: The Fastest Screen
Before running the full expense stack, investors use the gross rent multiplier (GRM) as a 5-second filter:
GRM = Purchase Price / Annual Gross Rent
On this duplex: $350,000 / $33,600 = 10.4 GRM
A GRM below 10 is a positive signal in most markets — you are paying less than 10 years of gross rent for the property. A GRM above 15 is a warning sign that the price is disconnected from rental income. This duplex at 10.4x is in an acceptable range, but the full expense analysis above shows the actual cash flow is negative.
GRM ignores operating expenses — it only measures the price-to-rent relationship. Use it to screen properties quickly (anything above 14x GRM, skip). Then run the full NOI and cash-on-cash analysis on the ones that pass.
When the Deal Makes Sense Despite Negative Cash Flow
Not every rental property investment requires positive cash flow from day one. In appreciating markets, investors accept negative monthly cash flow in exchange for long-term appreciation and equity growth. A $350,000 duplex in a market appreciating at 5% annually adds $17,500 in value per year — significantly more than the $2,208 annual negative cash flow in this scenario.
The decision calculus: if you believe the market will appreciate, if you have the liquidity to cover monthly shortfalls, and if the tax benefits (depreciation, expense deductions) offset part of the carrying cost, slightly negative cash flow can be an acceptable trade-off. In flat or declining markets, negative cash flow with no appreciation upside is simply a loss.
This article provides general real estate information for educational purposes. Consult a licensed real estate professional for advice specific to your market and situation.
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