The 7 Numbers That Kill Most Rental Deals

Most bad rental deals don't look bad at first glance. The listing shows strong rent, the agent's pro forma shows positive cash flow, and the price feels reasonable. Then the real numbers arrive — and the deal quietly bleeds for years.

In almost every case, the autopsy points to one of seven numbers the buyer got wrong. Learn them and you'll kill bad deals in minutes instead of discovering them over years.

1. Vacancy — Budgeted at 0%, Lived at 8%

The listing's income line assumes the property is rented 365 days a year and every tenant pays in full. Reality: units sit empty between tenants, and some rent never gets collected.

Get it right: underwrite 5–8% vacancy and collection loss on single-family rentals, more in transitional areas. On a $2,100/month rental, the difference between 0% and 7% vacancy is $1,764 a year of phantom income — often the entire "cash flow" the listing advertised.

2. Maintenance — The 1%-Rule Fantasy

"Budget 1% of the property value per year for maintenance" is the most expensive rule of thumb in real estate. A 1970s house doesn't care about your rule — it needs what it needs.

Get it right: 5–8% of effective rental income for properties in decent condition, higher for older stock. And separate maintenance (fixing what's broken now) from CapEx (replacing what's wearing out) — lumping them together is how a $9,000 roof ambushes you in year three.

3. CapEx Reserves — The Line Everyone Skips

This is the number-one killer. Beginners budget for the water heater that broke; they don't budget for the roof, HVAC, driveway, and appliances that are all quietly aging on schedule.

Get it right: amortize every major component. Roof: cost ÷ remaining life. HVAC: cost ÷ remaining life. Water heater, appliances, flooring — same math. A $9,000 roof with 15 years left is $50/month. A $6,000 HVAC with 10 years left is another $50/month. These aren't pessimism; they're physics.

4. Property Management — "I'll Self-Manage" (For Now)

Self-managing shows 0% on the spreadsheet and costs plenty in reality: your evenings, your weekends, your 2 AM plumbing calls. Worse, it makes the deal uncomparable — and unsellable to any buyer who won't self-manage.

Get it right: underwrite 8–10% for management even if you'll do it yourself. If the deal only works at 0% management, it doesn't work. Your time has a price; the spreadsheet should know it.

5. Property Taxes — Priced at the Seller's Basis

The listing shows the seller's tax bill — based on what they paid years ago. In most states, the sale triggers a reassessment at your purchase price.

Get it right: estimate taxes on your purchase price using the local millage rate, then verify with the county. On a $285,000 purchase in a 1.5% effective-tax market, that's $4,275 a year — and reassessment alone can add five figures annually versus the seller's number.

6. Insurance — The Quote You Didn't Get

Insurance is the fastest-moving line item in rental underwriting. Roof age, prior claims, flood zone, and carrier pullbacks have doubled premiums for many owners in recent years — and the listing never reflects it.

Get it right: get an actual quote before you remove contingencies, not after closing. In coastal markets, budget for the possibility that the quote comes back 50–100% above your assumption, and know your walk-away number in advance.

7. DSCR — The Gate You Can't Negotiate

Debt Service Coverage Ratio — NOI divided by annual mortgage payments — is the number your lender cares about most. Most residential investment lenders want 1.20–1.25x. Below 1.0, the property doesn't cover its own mortgage.

Get it right: underwrite to the lender's number, not yours. A deal that needs 1.10x DSCR to pencil out isn't a deal you can finance — which makes it a deal you can't buy, no matter how good the cap rate looks.

The Pattern

Notice what the seven numbers have in common: every one of them is an expense or financing reality the seller's marketing conveniently minimized. The rent number is the least important number in the analysis — it's the costs that determine whether you keep any of it.

The fix is structural, not motivational: run every deal through the same line-by-line sequence — effective income, full opex budget, NOI, then cap rate, cash-on-cash, and DSCR — and set kill switches in advance. A deal that fails a kill switch is a no. No "but the neighborhood is up-and-coming."

If you want that discipline in a box, the Complete Deal Pack https://dealready.gumroad.com/l/ublvr includes the SFR and multifamily proformas that run this exact sequence, plus a 100-point Go/No-Go scoring framework with 10 hard kill switches — the system that forces the "no" your gut won't say.

Educational content, not financial advice. Verify rents, taxes, insurance, and expenses against your local market before making investment decisions.