Article Summary
- A property's advertised rent minus its mortgage payment is not its actual cash flow — vacancy, maintenance, capital repairs, and property management fees all eat into that number before it's real profit.
- Investment-property mortgages are underwritten differently from a primary-residence loan: lenders typically want a larger down payment and charge a somewhat higher rate, since a rental carries more default risk in a lender's eyes than a home you live in.
- Hiring a property manager typically costs a percentage of collected rent, which sounds expensive until you price in the time, stress, and mistakes of self-managing tenants you've never screened before.
"The best investment on earth is earth."
Louis Glickman
It's easy to fall in love with a listing's projected numbers — a duplex, two tenants already in place, rent that on paper covers the mortgage with a few hundred dollars left over. The spreadsheet the seller's agent hands over almost never accounts for the roof that's twelve years old, the month the unit sits empty between tenants, or the 2 a.m. call about a broken water heater. Rental property can build real wealth over time through mortgage paydown, appreciation, and cash flow, but only for buyers who price in the boring, unglamorous parts before they sign anything, not after.
Running the Numbers Before You Buy
Two figures worth understanding before evaluating any rental are cap rate and cash-on-cash return. Cap rate is a property's annual net operating income (rent minus operating expenses, not including the mortgage) divided by its purchase price, and it's a rough way to compare properties independent of how they're financed. Cash-on-cash return instead measures actual cash flow after the mortgage payment, divided by the cash actually invested, which is usually the more relevant number for someone financing the purchase rather than paying cash.
Some investors use quick heuristics like the so-called "1% rule" — monthly rent should be roughly 1% of purchase price — as a fast initial screen for whether a deal is worth digging into further, but these rules of thumb vary a lot by local market and shouldn't substitute for a full expense breakdown. A property in a lower-priced market might clear that bar easily while offering weak appreciation prospects, while a property in an expensive, high-appreciation market might never come close to it and still be a reasonable long-term hold. Treat any single ratio as a filter to decide what's worth analyzing further, not as a verdict on its own.
Financing and Cash Flow Reality
Lenders generally treat investment properties as higher risk than owner-occupied homes, which typically shows up as a larger required down payment and a somewhat higher interest rate than you'd get financing a home you plan to live in. It's worth getting pre-approved for investment-property financing specifically, rather than assuming the terms from a past home purchase will carry over, since underwriting standards and reserve requirements for landlords are often stricter.
Once financed, real cash flow needs to account for more than the mortgage payment: property taxes, insurance (often pricier for a non-owner-occupied policy), a maintenance reserve for the routine wear a tenant-occupied property generates, and a separate capital expenditure reserve for big-ticket items like a roof, furnace, or water heater that will eventually need replacing. Vacancy also needs to be budgeted honestly — even a well-managed rental will sit empty between tenants occasionally, and a property whose cash flow only works at 100% occupancy isn't really cash-flowing at all.
Being a Landlord (Or Hiring One)
Self-managing a rental means handling tenant screening, lease agreements, rent collection, maintenance requests, and the occasional difficult conversation about a late payment or a lease violation, all while staying compliant with fair housing law and local landlord-tenant regulations, which vary significantly by state and city. Done well, it saves the management fee entirely and keeps an owner closer to their asset; done poorly, it can mean bad tenant selection, missed legal requirements, or simply more stress than the return justifies.
A property manager typically charges a percentage of collected rent plus sometimes a placement fee for finding new tenants, and in exchange handles screening, day-to-day communication, and coordinating repairs. For an out-of-state owner, someone with a demanding job, or a first-time landlord who'd rather learn the business gradually, that fee often buys real peace of mind — the tradeoff is less direct control and a cut taken out of the property's cash flow before it reaches the owner.
A Framework Before You Sign
Before making an offer, build a full expense worksheet — mortgage, taxes, insurance, maintenance reserve, capital expenditure reserve, vacancy allowance, and management fee if applicable — and see whether the property still cash-flows under those conservative assumptions, not the seller's optimistic ones. Get a professional inspection regardless of how good the property looks; a rental's profitability can be quietly wiped out by a major repair discovered after closing that a pre-purchase inspection would have flagged.
Decide on self-managing versus hiring a manager before closing, not after the first difficult tenant situation forces the question, since that decision affects both your expected cash flow and how much ongoing time the property will actually demand from you. And build a real cash reserve specifically for the property — separate from personal emergency savings — before the first tenant moves in, so a slow month or an unexpected repair doesn't become a crisis that forces a bad decision.