Lease-up risk is the stretch of months a newly delivered building produces no meaningful income while it fills to stabilization. The concrete is poured, the loan is drawn, the taxes and insurance are due, and the rent roll is close to empty. Most underwriting models treat this period as a line item and move on. It is not a line item. It is the phase where a new development is most fragile, because the building carries its full cost structure against a fraction of its income. A new building does not lease at the speed of its pro forma. It leases at the speed of the submarket, and the distance between the two is lease-up risk.
Key Takeaways
Lease-up risk is the period between delivery and stabilization when a new building carries full debt and operating costs against partial or zero income.
Stabilization is not full occupancy. Agency lenders including Fannie Mae and Freddie Mac generally treat roughly 90% occupancy, sustained for about 90 days, as stabilized.
Months to stabilization equals the units you must lease divided by the submarket's trailing net absorption. That single division governs the entire risk.
U.S. multifamily net absorption totaled 78,100 units in Q1 2026, per CBRE, against 58,100 units of completions. National demand is real but finite, and it is split across dozens of submarkets.
A worked 200-unit example carries roughly $293,000 per month in fixed cost and funds about $1.4 million of net carry before it reaches break-even occupancy.
What Is Lease-Up Risk in New Development?
Lease-up risk is the exposure a sponsor takes on between certificate of occupancy and stabilization, when a new development must pay its full debt service and operating expenses out of a rent roll that starts near zero. The building earns nothing on day one and earns its full income only at stabilization. The months in between are funded by the sponsor.
The risk has two independent drivers: how many units must be leased, and how fast the submarket absorbs them. A 200-unit tower and a 40-unit infill project face the same market absorption pace, but the tower carries five times the empty units against it. Size amplifies exposure. So does timing, because a building that delivers into a quarter of heavy competing supply absorbs slower than the same building delivered into a supply gap.
Underwriting, new development, and stabilization all hinge on one fact operators understate: absorption is finite and shared. The submarket does not lease your building in isolation. It splits its demand across every competing lease-up in the same radius.
How Long Does a New Building Take to Reach Stabilization?
A new building reaches stabilization when it holds the lender's occupancy threshold, commonly around 90%, for a sustained period. Industry underwriting for ground-up multifamily typically models roughly 12 to 18 months from delivery to stabilization, though the real answer is arithmetic: divide the units you must lease by the submarket's trailing monthly net absorption.
That division is the whole game. Absorption rate is the pace at which the submarket takes units off the market, and the submarket's absorption is what actually leases your building, not the metro headline. Hold the target constant at 186 leased units, 93% of a 200-unit building, and watch how the timeline moves with pace:
Trailing net absorption (units/month) | Months to reach 186 leased units |
|---|---|
10 | 18.6 |
15 | 12.4 |
20 | 9.3 |
25 | 7.4 |
30 | 6.2 |
The same building stabilizes in six months or nineteen depending only on the demand pace it delivers into. A pro forma that assumes 25 units per month in a submarket absorbing 12 is not aggressive. It is wrong, and the error compounds every month the building sits below its assumed curve.
National context sets the ceiling. CBRE reported U.S. multifamily net absorption of 78,100 units in Q1 2026, a rebound from 1,500 units of negative absorption in Q4 2025, against 58,100 units of completions. That national demand is split across the 69 markets CBRE tracks and further across submarkets. Your building competes for a sliver of it.
What Does the Lease-Up Carry Cost in Dollars?
The lease-up carry is the cash a sponsor funds to cover debt service and operating expenses until the building's own income covers them. It is the dollar measure of lease-up risk. The building reaches break-even occupancy well before stabilization, but every month below that line is funded from reserves or equity.
Work the example with stated inputs:
Input | Value |
|---|---|
Units | 200 |
Stabilization target | 93% (186 units) |
Delivered occupancy | 0 units |
Trailing net absorption | 15 units/month |
Average rent | $1,800/unit/month |
Monthly debt service (interest-only) | $233,000 |
Monthly operating expense (largely fixed) | $60,000 |
Total monthly carry is $293,000. Break-even occupancy is $293,000 divided by $1,800, or 163 units, about 82%. At 15 units per month, the building crosses break-even near month 11. Through those 11 months it accrues $3,223,000 of carry and collects roughly $1,782,000 in ramping rent, leaving about $1,441,000 the sponsor funds before the building pays for itself.
That $1.4 million is lease-up risk expressed in dollars. It is often buried inside a construction loan's interest reserve, which is why the interest reserve hides a construction deal's true break-even. The reserve keeps the loan current on paper while the building earns nothing, so the day the reserve runs dry, not the day the building stabilizes, is the date the underwriting must survive.
How Do You Underwrite Lease-Up Risk Before You Buy or Build?
You underwrite lease-up risk by sourcing the submarket's trailing net absorption, dividing your leasable units by it to get months to stabilization, then multiplying the monthly carry by that timeline. Anchor the absorption input to observed data, not to the pace the deal needs, and stress it downward by a third to see whether the reserve still holds.
Three tests separate a survivable lease-up from a dangerous one. First, does the interest reserve fund the full modeled lease-up plus a buffer for slippage? Second, is the absorption assumption at or below the submarket's trailing pace, or does it require the building to outperform the market? Third, what happens to break-even timing if competing supply delivers into the same window? A building underwritten to a 12-month lease-up that takes 18 burns six extra months of carry, and that gap is where new-development deals fail.
Frequently Asked Questions
What is the difference between lease-up and stabilization?
Lease-up is the active process of leasing a new building from delivery toward its occupancy target. Stabilization is the endpoint, the moment the building holds a sustained occupancy level, commonly around 90%, that lenders treat as a durable operating baseline.
Does a building earn nothing during lease-up?
It earns nothing at delivery and ramps as units lease, so it earns partial income through most of lease-up. The point is that income sits below full cost until the building crosses break-even occupancy, so the sponsor funds the gap the entire time.
How is months to stabilization calculated?
Divide the number of units you must lease to hit the stabilization target by the submarket's trailing monthly net absorption. A building needing 186 leased units in a submarket absorbing 15 units per month models about 12 months to stabilization.
Why does absorption pace matter more than the occupancy target?
The occupancy target sets the finish line, but absorption pace sets how long it takes to get there. Two identical buildings with the same 93% target stabilize months apart if one delivers into a submarket absorbing 25 units a month and the other into one absorbing 10.
Conclusion
Lease-up risk is not a footnote to a development pro forma. It is the months a new building carries its full cost against income it does not yet have. The size of that risk is set by two numbers an operator can source before committing capital: the units that must be leased and the submarket's trailing absorption pace. Divide one by the other and the timeline is no longer a hopeful assumption, it is arithmetic. Multiply that timeline by the monthly carry and lease-up risk stops being a concept and becomes a dollar figure the deal must be capitalized to survive. The operators who underwrite that figure honestly capitalize for the lease-up they will get. The ones who underwrite the pace the deal needs discover the difference after the reserve runs dry.