# Underwriting Development Risk and the Pro Forma
A developer buys a suburban parcel for $6 million, expecting to build 200 apartments and sell at stabilization for $70 million. Two years later, lumber and labor costs have run 15% over budget, the city took nine extra months to issue permits, and interest rates on the construction loan climbed. That $12 million profit projection is now $2 million, and one more bad quarter turns it negative. The land did not change. The math did.
Development is where real estate stops being about buildings and becomes about spreadsheets under pressure. This lesson walks a ground-up multifamily deal from raw land to stabilization, and shows exactly where profit and ruin diverge.
A pro forma is a projected financial model of a deal: costs going in, income coming out, and the return in between. For development, it has three phases stacked in time.
1. Acquisition and predevelopment. Buy the land, design, entitle, permit.
2. Construction. Draw down a loan, pay contractors, build.
3. Lease-up and stabilization. Fill the units, hit target occupancy, then sell or refinance.
Each phase carries a distinct risk. Underwriting means pricing all three before you commit capital.
Land basis is your all-in cost for the dirt: purchase price plus closing costs, brokerage, and any carrying costs before you build. Say the parcel is $6 million all-in.
Land basis is the anchor. Overpay here and no amount of construction discipline saves you, because every downstream number is measured against a cost you already locked in. A useful rule of thumb professionals cite: land should be roughly 15% to 20% of total project cost for suburban multifamily, higher in dense urban markets. If land is 40% of your budget, the deal is fragile before you break ground.
Total development cost has three big buckets.
Hard costs. The physical build: concrete, framing, mechanical systems, finishes. For garden-style suburban multifamily in 2026, hard costs are commonly estimated in the range of $150 to $250 per square foot, though this varies widely by market and product type. This is your largest and most volatile line.
Soft costs. Everything not physical: architecture, engineering, legal, permits, insurance, and marketing. Typically 15% to 30% of hard costs.
Financing costs. Loan fees plus interest paid during construction, when the building earns nothing.
You do not pay the whole build at once. A construction loan funds through draws: periodic disbursements the lender releases as work is completed and inspected. A typical structure is a loan-to-cost (LTC) ratio, the share of total cost the lender will finance, often 60% to 70% for development in a cautious 2026 credit environment.
Here is the trap. Interest accrues on the drawn balance. The longer construction runs, the more months of interest you carry with zero rent coming in. This is why timing delays are not just annoying: they are a direct financial cost.
For a working introduction to how these budgets are assembled, the Urban Land Institute publishes accessible primers on development finance fundamentals.
Two variables destroy more development deals than any market crash.
Assume a $50 million hard-cost budget. A 15% overrun is $7.5 million of unplanned spend. If your projected profit was $12 million, you just erased more than half of it with a single number that construction veterans will tell you is common, not extreme.
Developers protect against this with a contingency: a reserve line, usually 5% to 10% of hard costs, set aside for the unexpected. A deal with a 3% contingency in a volatile materials market is underwriting optimism, not risk.
Delays hit three ways at once:
A nine-month permitting delay on a large project can easily add seven figures in carry alone. Time is the one input a developer controls least and pays for most.
🎬 [VIDEO: "How to Build a Real Estate Development Pro Forma" — https://www.youtube.com/results?search_query=real+estate+development+pro+forma — a step-by-step walkthrough of building a development model from land to stabilization]
Construction ends and the building sits empty. Now you must fill it.
Lease-up is the period from first move-in to stabilized occupancy, the point where the property hits a normalized occupancy level, commonly modeled at 93% to 95%. Lease-up takes time. A 200-unit project leasing at 15 to 20 units per month takes roughly ten to thirteen months to stabilize, and every one of those months carries expenses against partial income.
Two levers matter here:
Here is the single most important number in development underwriting.
Yield on cost (YoC), also called development yield or return on cost, is your stabilized net operating income divided by total project cost.
Net operating income (NOI) is annual rental income minus operating expenses, before debt and taxes.
$$\text{Yield on Cost} = \frac{\text{Stabilized NOI}}{\text{Total Development Cost}}$$
Suppose stabilized NOI is $5.4 million and total cost is $72 million. Yield on cost is 7.5%.
Now compare yield on cost to the market cap rate: the yield an investor would accept to buy a finished, stabilized building. A cap rate is NOI divided by property value, so a lower cap rate means a higher price.
If similar stabilized buildings trade at a 5.5% cap rate, and you built to a 7.5% yield on cost, your development spread is 200 basis points (a basis point is one hundredth of a percent, so 200 bps equals 2%).
That spread is your profit margin for taking development risk. It works like this:
Developers generally want a spread of at least 150 to 200 bps to justify the risk versus simply buying an existing building. When cost overruns push yield on cost down toward the market cap rate, the spread vanishes, and with it the entire reason to develop.
Knowledge check
1. The lesson opens with a deal whose projected profit collapsed from $12 million to $2 million while 'the land did not change.' What core concept about development risk does this illustrate?
2. Why is land basis described as 'the anchor' that must be underwritten carefully before anything else?
3. A pro forma organizes a development into three phases stacked in time (predevelopment, construction, lease-up). Why does the lesson emphasize this phased structure?
4. Select ALL correct answers. According to the lesson, which of the following are properly included in a development's land basis?
Select all the correct answers.
5. Select ALL correct answers. What does the 'land should be roughly 15%–20% of total project cost' rule of thumb help an underwriter reason about?
Select all the correct answers.
Let us stack the phases into one picture.
| Line | Amount |
|---|---|
| Land basis | $6.0M |
| Hard costs | $50.0M |
| Soft costs | $12.0M |
| Financing costs | $4.0M |
| Total development cost | $72.0M |
| Stabilized NOI | $5.4M |
| Yield on cost | 7.5% |
| Value at 5.5% cap | $98.2M |
| Projected profit | ~$26M |
Now stress it. Apply a 15% hard-cost overrun ($7.5M) and a rent miss that cuts NOI to $5.0M:
The spread compressed from 200 bps to 80 bps. Profit fell by more than half. Push the overrun and delay further, or let cap rates rise to 6.5%, and the deal approaches breakeven. This sensitivity is the entire game.
Sophisticated developers never present a single number. They model ranges: cost up 5%, 10%, 15%; lease-up slow by three months, six months; exit cap rate up 50 or 100 bps. The output is not one profit figure but a