Two numbers every investor should run before they commit to a deal

Rental Property Investor · Palo Alto, CA · Member since 2026 · 42 posts · 22 votes

5mo

That’s a great way to frame it, especially the break-even occupancy piece. I feel like that number alone gives a much clearer sense of margin of safety than most pro formas.

I’ve been seeing something similar when running downside scenarios, once you get closer to that break-even point, even small changes in vacancy or expenses start to compound pretty quickly.

I’ve actually been trying to standardize that kind of stress testing across deals so it’s easier to compare them consistently, instead of relying on a single set of assumptions each time.

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Gavin Vitale
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Investor · Mill Valley, CA · Member since 2026 · 8 posts · 3 votes
5mo
Quote from @Hasan Gabareen:

That’s a great way to frame it, especially the break-even occupancy piece. I feel like that number alone gives a much clearer sense of margin of safety than most pro formas.

I’ve been seeing something similar when running downside scenarios, once you get closer to that break-even point, even small changes in vacancy or expenses start to compound pretty quickly.

I’ve actually been trying to standardize that kind of stress testing across deals so it’s easier to compare them consistently, instead of relying on a single set of assumptions each time.
Exactly right on the compounding effect. Once you're close to break-even the math gets unforgiving fast. A 2% swing in vacancy or a single unexpected expense can flip the whole picture. That's why I build the stress scenarios before I ever run a base case, it reframes how you look at the deal from the start rather than trying to justify numbers you already like.

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Jose Cortes

Member since 2026 · 11 posts · 2 votes

5mo

Great post. I agree that many investors only look at the upside and do not prepare for the worse case scenario. I try to remind investors who come to me for help that a proforma is what a seller or broker anticipates what the market will allow not actual. I typically take market rent and subtract $100 or $150. If the deal still works I take a deeper dive.

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Gavin Vitale
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Investor · Mill Valley, CA · Member since 2026 · 8 posts · 3 votes
5mo
Quote from @Jose Cortes:
Great post. I agree that many investors only look at the upside and do not prepare for the worse case scenario. I try to remind investors who come to me for help that a proforma is what a seller or broker anticipates what the market will allow not actual. I typically take market rent and subtract $100 or $150. If the deal still works I take a deeper dive.

That's a solid discipline. Subtracting $100-150 from market rent as a starting assumption forces the deal to earn its way back up rather than starting at the optimistic ceiling. The investors who get in trouble are almost always the ones who underwrote to what the market "should" do rather than what it's actually doing right now.

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Gavin Vitale

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Investor · Mill Valley, CA · Member since 2026 · 8 posts · 3 votes

5mo

That's a solid discipline. Subtracting $100-150 from market rent as a starting assumption forces the deal to earn its way back up rather than starting at the optimistic ceiling. The investors who get in trouble are almost always the ones who underwrote to what the market "should" do rather than what it's actually doing right now.

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Dominic Mazzarella

Investor · Hendersonville, NC · Member since 2016 · 498 posts · 285 votes

5mo

Quote from @Gavin Vitale:

In 2009 I was buying homes at courthouse auctions across Northern California. One walkthrough, no second look, renovation budget estimated on the spot. We did that 400 times and deployed over $100 million for institutional investors.

The single biggest mistake I watched other buyers make during that run wasn't overpaying. It was trusting seller projections without stress testing them.

Every pro forma shows you the ceiling. Full occupancy, optimistic rents, minimal expenses. Nobody hands you a document that shows what happens when things go slightly sideways.

Before committing to any deal I run three scenarios. Base case with current market rents and realistic vacancy. Conservative with rents 8% below market and vacancy pushing 12%. Downside with rents 15% off and vacancy at 20%.

If the deal survives scenario two it's worth pursuing. If it only works in scenario one you're not investing, you're just betting everything goes right.

The other number nobody talks about is break-even occupancy. Take your total annual costs, divide by gross potential rent, and you know exactly how much vacancy the deal can absorb before it stops covering itself. Above 85% and you have almost no cushion. Below 75% and you have room to breathe.

Run both before you run anything else.

I like your approach. The break-even occupancy is the kind of metric that can save your *** when the market shifts or something unexpected comes up. Too many investors just plug optimistic numbers into a spreadsheet and call it a day. Running multiple stress tests on rents and vacancy gives you a realistic view of risk, not just potential reward. If a deal only works when everything is perfect, you’re gambling, not investing. I’d add to watch your rehab and operating expense assumptions closely too, because those are often where the optimism creeps in without people realizing it. If you don’t build in cushion on both income and costs, you’re setting yourself up for surprises.

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Masoud ArouniPro Member

Investor · Pleasanton, CA · Member since 2026 · 119 posts · 52 votes

5mo

@Gavin Vitale the three-scenario framework and break-even occupancy are the right starting tools. The piece missing from most stress tests including this one is the reserve allocation layer.

Break-even occupancy tells you when rent stops covering fixed costs. It does not tell you whether you survive a roof replacement or HVAC failure in the same year your vacancy spikes. I allocate 5% of gross rent to reserves before I run any scenario, that number comes off the top before cash flow is calculated. It is not glamorous but it is what separates a deal that survives a bad year from one that requires a capital call.

The other thing worth adding is compounding the stresses rather than running them separately. Scenario two with rents 8% below market and 12% (1.5m) vacancy is useful. Scenario two plus a 12000 CapEx event in year one is where most deals actually reveal their true margin. The income stress and the expense stress rarely happen in isolation in a real downturn.

400 auction buys in Cal in 2009, that is a real data set. What break-even occupancy threshold were you actually seeing separate the deals that performed from the ones that did not?

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Two numbers every investor should run before they commit to a deal

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