The 1% Rule Is Dead: How Rental Investors Actually Underwrite Deals Now

For years, rental investors leaned on a simple screen: if a property's monthly rent equals at least 1% of its purchase price, it is probably worth a closer look. A $200,000 house renting for $2,000 passed. The rule was fast, memorable and briefly useful. Today it fails almost everywhere a typical investor wants to buy, and clinging to it leads either to paralysis or to bad deals in neglected neighborhoods. Here is what replaced it.

Why the shortcut stopped working

The 1% rule became popular in the years after the 2008 housing crash, when foreclosures pushed home prices well below replacement cost in many cities while rents held relatively steady. Rent-to-price ratios of 1% or better were common, sometimes even in decent suburbs. As prices recovered and then climbed faster than rents through much of the following decade, the ratio compressed. In many coastal and fast-growing metros, a ratio of 0.5% to 0.7% is now more typical for a well-located house.

The deeper problem is that the rule was never underwriting. It ignores property taxes, which vary enormously from state to state. It ignores insurance, which has risen sharply in several regions exposed to hurricanes, wildfire and hail. It ignores the age of the roof, the HVAC system and the plumbing. Two houses with identical rent-to-price ratios can produce wildly different returns once those costs are counted.

A ratio tells you a property is cheap relative to its rent. It cannot tell you whether the rent will survive the expenses.

Start with net operating income

Modern underwriting begins by building net operating income (NOI) from the ground up. NOI is income after operating expenses but before mortgage payments. It is the number that determines value, and it forces you to account for every cost a property actually carries.

Consider an illustrative single-family rental priced at $340,000 with market rent of $2,400 per month. That is a ratio of about 0.7%, a clear fail under the old rule. Here is how it underwrites line by line:

Notice the capital reserve line. Many beginners skip it because nothing breaks in year one. But a $12,000 roof and an $8,000 HVAC replacement will arrive eventually, and setting money aside annually is the only honest way to reflect that in returns.

Add the financing layer

NOI tells you what the property earns. Financing tells you what you keep. Two metrics matter most once debt enters the picture.

Debt service coverage ratio (DSCR) divides NOI by annual mortgage payments. Lenders offering investor loans often look for a DSCR of roughly 1.2 or higher. Assume our example is financed with 25% down ($85,000) and a 30-year loan of $255,000. At an illustrative 7% interest rate, annual principal and interest come to about $20,360. The DSCR is $15,960 divided by $20,360, or about 0.78. The property does not cover its own debt, and the owner would feed it roughly $4,400 a year.

Cash-on-cash return divides annual pre-tax cash flow by the total cash invested, including down payment, closing costs and initial repairs. With negative cash flow, this deal's cash-on-cash return is negative. At a 5.5% illustrative rate, payments drop to about $17,370, and the shortfall narrows to around $1,400. The same house is a very different investment depending on the cost of money.

Total return, not just cash flow

Here is where investors who abandoned the 1% rule split into two camps. One camp insists on positive cash flow from day one and buys in markets where prices and rents still allow it, often smaller Midwestern and Southern cities. The other accepts thin or slightly negative cash flow in exchange for stronger expected appreciation, rent growth and principal paydown in higher-cost metros.

Both approaches can work, but the second one requires honesty about what you are betting on. Total return combines four components:

1. Cash flow: rent after expenses and debt service.
2. Principal paydown: the portion of each mortgage payment that reduces the loan balance.
3. Appreciation: growth in property value, which is uncertain and varies widely by market and era.
4. Tax benefits: depreciation deductions that can shelter rental income, subject to IRS passive activity rules and recapture at sale.

A deal that only works because of appreciation is a speculation, which is fine if you can afford to carry it through a flat or falling market. Know which kind of investment you are making before you sign.

Stress test before you commit

A single set of projections is a guess. Underwriting becomes useful when you ask what happens if things go wrong. Run at least these scenarios:

• Rent 10% below your estimate: listing rents and achieved rents often differ, especially for a first lease.
• Vacancy of two months in a year: a slow turnover plus make-ready work can easily cost that much.
• Insurance and taxes up 20%: reassessment after a sale is common in many states, and premiums can reprice at renewal.
• A major repair in year two: can you fund a $10,000 surprise without selling or borrowing at a bad time?

International buyers should add a few lines of their own: currency movement between their home currency and the dollar, US tax filing costs and potential withholding on rental income. A CPA familiar with nonresident rental owners can help set these assumptions correctly.

Replacing the rule with a process

The 1% rule was appealing because it was a single number. Its replacement is a repeatable process: build NOI from verified line items, layer in realistic financing, calculate DSCR and cash-on-cash return, decide honestly how much you are relying on appreciation, then stress test the result. It takes an hour rather than ten seconds, but it is the hour that separates investors who build portfolios from those who inherit problems. Use a quick ratio, if you like, to sort listings. Just never let it make the decision.