Commercial underwriting from rent roll to investment return

Commercial underwriting is the process of testing whether a property’s documented income, physical requirements, financing, and future resale can support the price and capital an investor must commit. Begin with the leases and operating evidence. Build a dated cash-flow model. Then ask which assumptions drive the result and what happens when they fail together.

A commercial building is both a physical asset and a set of contractual cash flows. Its square footage does not pay the mortgage. Tenants must be able to use the space, remain economically viable, and satisfy enforceable obligations; the owner must operate the building and fund the promises made in the leases.

This guide provides an acquisition framework for Chicago-area investors. It uses hypothetical numbers to demonstrate analysis, without claiming current rents, capitalization rates, lending terms, or tax forecasts. The same framework applies across retail, industrial, office, mixed-use, and other income-producing assets, while the inputs and risks differ substantially.

1. Write the investment question before opening the spreadsheet

State what the investor is buying and why it should work. “An industrial building in Chicago” is a description. A thesis identifies an achievable source of return: current durable rent, renewal of below-market leases, subdivision for smaller tenants, operating improvement, or another supported plan.

Write three versions of the outcome. The base case states the expected execution. The downside identifies a plausible combination of setbacks. The failure case identifies a condition that invalidates the acquisition rather than merely reducing the return. A prohibited use, unaffordable structural repair, or inability to fund the exit may belong in the failure case.

List what must be learned before a purchase becomes unconditional. Assign an owner and deadline to each question. This is more useful than producing a hundred-page diligence folder without identifying which findings change the price or decision.

Define the intended holding period, investor liquidity limits, and maximum additional capital. An attractive long-term unlevered return may be unsuitable for an investor who cannot fund an early leasing event. Strategy and capital capacity belong in the model from the beginning.

2. Establish the physical and legal investment boundary

Verify the interest being acquired, parcel configuration, building area, access, parking rights, and intended use. A brochure’s description is a starting assertion. Title, survey, leases, municipal records, inspections, and professional review establish different parts of the picture.

For industrial property, record loading, clear height, power, truck movement, floor condition, sprinklers, and expansion limitations. For retail, investigate visibility, access, parking, signage, shared facilities, and use restrictions. For office, examine floor plates, building systems, elevators, accessibility, and tenant delivery condition. Mixed-use underwriting must also address interactions between uses.

A physical characteristic affects value through tenant demand, achievable rent, required capital, or the exit market. Describe that connection explicitly. “Older building” is less informative than “the proposed tenant requires electrical capacity that is not documented, and an upgrade could change both budget and commencement date.”

For Chicago and the surrounding metropolitan area, identify the relevant municipality and county. Zoning, permitting, taxes, and records differ. Do not import a City of Chicago requirement into a suburban investment without checking jurisdiction.

3. Build the lease abstract and rent roll together

The rent roll summarizes occupancy. The leases and amendments establish contractual economics. Create a row for each tenant and preserve links to the supporting documents.

Capture rentable area, premises, permitted use, commencement and expiration, current and future rent, concessions, renewals, reimbursements, deposits, guarantees, assignment rights, termination rights, exclusives, co-tenancy, and landlord obligations. A second reviewer should be able to locate the clauses supporting every material input.

Separate signed leases, proposals, letters of intent, and speculative market rent. They represent different evidence levels. A prospective tenant expressing interest should not become contracted revenue in the base case.

Record disputed amounts and unusual side agreements. A tenant estoppel can provide important transaction evidence, but its scope and reliance depend on the actual document. Obtain counsel’s review where interpretation matters rather than assume a summary proves every obligation.

Plot expirations by year and by contribution to revenue. Ten percent of area can produce more than ten percent of income. A concentration analysis should include both area and dollars, along with tenant relationships that create correlated exposure.

4. Reconcile contractual rent with collectible income

Use monthly billing, receivables, and deposits to distinguish scheduled rent from cash collected. Investigate arrears and concessions rather than assuming they are temporary. A tenant can remain physically present without producing the expected economic income.

For each vacant space, model a credible timeline from marketing to occupancy to rent commencement. Include delivery work, permits, tenant improvements, and free rent. A lease signed in October may not produce a full quarter of rent by December.

Maintain separate views for in-place operations, the first ownership year, and stabilized operations. This prevents a future annual rent figure from being inserted into the acquisition year without its costs and delay.

Recoveries require their own schedule. Calculate the eligible expense pool, allocation, exclusions, caps, base years, and collectible amounts. Do not treat NNN as a universal promise that all expenses move to tenants. The subject leases determine the economics.

Kimco’s public annual filing is a useful real-world reference for the range of retail lease and investment disclosures. Its portfolio is not a substitute for the subject building’s contracts or local comparables. Kimco 2025 Form 10-K

5. Rebuild operating costs from evidence

Collect a multi-year history with monthly detail, invoices, current contracts, and known future obligations. Ask what the seller pays, what the buyer will pay, and what is currently omitted or deferred.

Normalize management cost, insurance, property taxes, utilities, repairs, administrative costs, and other property operations using a consistent convention. An owner who performs unpaid work has not eliminated the task. A buyer must either perform it personally or budget the cost.

Distinguish timing from a lasting change. A large annual payment can distort a month. A new service contract can change the future expense level. A deferred maintenance problem can make the historical cost misleading in the other direction.

Use an adjustment register with original amount, change, reason, support, and resulting amount. Apply the same skepticism to nonrecurring income and nonrecurring expenses. Removing one-time repairs while retaining a one-time lease termination payment biases the conclusion.

For a Chicago-area parcel, research the actual tax records and circumstances. A projected assessment, a tax bill, an appeal, and a hypothetical buyer’s tax estimate are different things. If the exposure is material, obtain a property-specific analysis rather than a blanket assumption.

6. Separate NOI from capital and distributions

For this framework, NOI is effective property revenue less property operating expenses, before financing and the separately identified capital costs. State the definition because terminology varies among lenders, managers, and models.

Fannie Mae defines its multifamily NCF as NOI less underwritten replacement-reserve expense. That specific convention illustrates why a model must name the measure it uses rather than assume every NCF line has the same content. Fannie Mae NCF definition

A property’s roof, tenant buildout, leasing commissions, and operating reserve can consume cash even when they are outside the stated NOI definition. Deduct or fund them explicitly. A reserve transfer and a contractor payment must be linked to avoid double counting.

Distributions are a later decision. Debt terms, reserve obligations, working capital, and the ownership agreement determine how much cash can be released and how it is allocated. NOI divided by equity is not a distribution yield.

7. Construct a complete hypothetical operating case

Assume a multitenant commercial property has $800,000 of potential annual base rent. In the first modeled stabilized year, vacancy and collection allowances reduce that by $80,000, leaving $720,000. Collectible expense recoveries contribute $160,000 and other income contributes $20,000. Effective revenue is $900,000.

Operating expenses total $360,000, producing $540,000 NOI. A $30,000 recurring reserve reduces the next cash-flow line to $510,000. Assume scheduled tenant improvements and commissions in that year total $90,000 and debt service totals $330,000. Cash remaining before further retention is $90,000.

This is one year, not a complete return model. It shows why the income chain matters. An advertised $540,000 NOI does not imply that owners can receive $540,000. Nor does the $90,000 establish the first acquisition year’s cash flow if leasing events differ.

8. Balance sources and uses before measuring returns

Include purchase price, diligence and closing costs, physical capital, leasing capital, financing costs, reserve funding, and contingency. Then identify initial debt, future committed draws, seller financing if permitted, and equity.

Suppose total uses are $8 million and total debt funding is $4.8 million. Required equity is $3.2 million. If projected annual cash available to the ownership entity is $90,000, its cash-on-cash measure is approximately 2.81% before individual allocation, using the stated full equity basis.

A seller might instead market the property’s cap rate based on NOI and purchase price. That can be an appropriate separate metric. The problem arises when one ratio is represented as the other or when closing reserves and later equity are omitted from the return denominator.

Add a monthly funding schedule for the first year and construction or rollover periods. Total committed capital can be sufficient while timing is inadequate. Reimbursement draws, retentions, and delayed collections can create a shortfall before a full-year model reveals it.

9. Underwrite the debt as a contract

Record note rate or index and spread, floors, payment frequency, amortization, maturity, extension conditions, prepayment provisions, guarantees, covenants, reserves, and cash management. A short marketing description does not resolve those obligations.

Calculate LTV, DSCR, and debt yield using the lender’s accepted inputs. Identify the controlling constraint rather than arguing only about the maximum leverage percentage. Reconcile differences between the investor’s NOI and lender’s cash flow.

A lender can support a smaller loan even when the property meets an advertised LTV. Conversely, a low monthly payment during interest-only does not show that the eventual refinance will work. Calculate maturity payoff and exit proceeds separately.

The OCC handbook treats income generation, coverage, leverage, and loan structure as related underwriting subjects. Its supervisory context is useful, while actual borrower obligations come from the transaction documents. OCC CRE lending handbook

10. Model the exit without hiding its contribution

Choose a stated disposition or refinance year. Use the appropriate subsequent income period for the valuation convention and document it. Apply an explicit exit cap rate, sale costs, debt payoff, and any other exit obligations.

Assume a later NOI of $600,000. At an illustrative 7.5% cap rate, gross value is $8 million. At 8.5%, it is approximately $7,058,824. If the model depends on the first value to repay debt and return equity, the investment has meaningful exit sensitivity.

Subtract selling costs before calculating equity proceeds. A 2% assumed cost on $8 million is $160,000; this is a modeling assumption, not a local fee quote. If debt payoff is $4.4 million, proceeds before taxes and other adjustments are $3.44 million. At the 8.5% value and the same cost percentage and debt, proceeds are approximately $2,517,647.

Keep tax analysis separate unless it has been explicitly modeled with appropriate professional input. A pre-tax IRR cannot be described as an after-tax investor return.

11. Use return metrics together

Cash-on-cash measures a period’s cash relative to a defined equity basis. Equity multiple measures cumulative distributions relative to total contributions. IRR accounts for timing under its mathematical assumptions. Each can reveal a different part of the investment.

A fast return of capital can improve IRR without increasing the total dollars earned. A long hold can produce a high multiple while delivering a modest annualized return. A refinance distribution can accelerate cash while increasing remaining debt exposure.

Report the dated contribution and distribution schedule alongside the metrics. Clarify whether an exit amount is gross property proceeds, net entity cash, or an individual investor allocation. If the ownership waterfall is not modeled, do not label property-level returns as a limited partner’s actual return.

Test unusual cash-flow patterns carefully. Multiple sign changes can make conventional IRR calculations ambiguous. A model should not select whichever mathematical answer looks best without explaining the issue. Present net cash totals and a consistent alternative measure when appropriate.

12. Stress connected variables together

A realistic downside is a causal story. A tenant departure can reduce rent and recoveries, increase improvements and commissions, weaken valuation, and reduce refinance capacity. Moving each input independently may understate that combined effect.

For the hypothetical property, reduce base rent collections by another $80,000, lose $20,000 of recoveries, and add $10,000 of operating cost. NOI falls from $540,000 to $430,000. With the same $30,000 reserve, $90,000 leasing capital, and $330,000 debt service, cash becomes negative $20,000.

If that same departure requires an additional $100,000 of leasing capital, the funding need rises to $120,000 before other changes. Identify where it comes from and whether the owners have committed it. The downside model should produce a decision about liquidity and price rather than merely a red cell.

13. Turn diligence findings into a decision memo

Summarize the thesis, evidence, price, funding, returns, material risks, unresolved items, and approval conditions. Keep the memo short enough to compare with the next quarter’s results. Preserve the original model and a dated assumption register.

For each major assumption, state the supporting evidence and what would disprove it. A leasing broker’s estimate, executed proposal, and completed comparable transaction provide different levels of support. Do not give uncertainty an invented precise probability just to produce a weighted average.

Identify the highest-impact questions first. A small utility variance may deserve correction, but an undocumented legal use or unfunded tenant obligation can determine whether the transaction is viable. The memo should show why the investor believes the major risks are manageable.

When seeking financing, submit the rent roll, operating history, source-and-use schedule, capital scope, and cash-flow bridge together. Jaken’s commercial asset-class overview helps frame the financing category without replacing property-specific underwriting. Jaken commercial property financing

14. Continue underwriting after closing

Compare actual performance with the acquisition case monthly or quarterly. Reconcile collections, recoveries, expenses, capital spending, debt balances, and reserves. Separate forecast errors from management execution and external changes.

If leasing takes longer, update cash and maturity consequences immediately. If a tax or insurance estimate changes, carry it through recoveries, NOI, coverage, value, and investor cash. A business plan should evolve with evidence while the original assumptions remain available for accountability.

The goal is a reproducible investment decision. Another informed person should be able to trace the major numbers from documents through cash flow to returns, understand where judgment enters, and see what happens if the plan fails. That is the difference between a commercial acquisition model and a spreadsheet that merely calculates the desired answer.

Model controls that prevent avoidable mistakes

Separate inputs from calculations and outputs. Give each material assumption a unit: dollars per square foot per year, dollars per month, percentage of eligible expenses, or a particular dated cash flow. Mixing annual rent with monthly costs can create a model that looks plausible while being wrong by a factor of twelve. Clearly distinguish usable area, rentable area, and the area basis in each lease.

Use control totals. Tenant area plus vacant area should reconcile to the adopted building area. Tenant-level rent should reconcile to the property revenue schedule. Debt opening balance plus draws minus principal paid should equal ending balance. Opening cash plus inflows minus outflows should equal closing cash. Sources must equal uses. A failed control should appear visibly rather than being hidden by a balancing plug.

Keep historical evidence separate from forecasts. An investor should be able to change a future rent assumption without accidentally rewriting the seller’s historical rent. Avoid hard-coded subtotals buried inside formulas. Document overrides and unusual conventions, particularly around rent commencement, partial months, debt draws, and sale-year cash flows.

Independently recalculate several key outputs using simple arithmetic. Verify at least the first debt payment, the major tenant’s rent step, a CAM recovery, the sources-and-uses balance, and terminal proceeds. A spreadsheet can contain internally consistent formulas that still describe the wrong transaction. The test is whether the model implements the documented economics.

Match the business plan to the owner’s capabilities

A value-add plan needs more than a spread between current and projected NOI. Identify who will lease the property, manage work, approve invoices, report to investors, and negotiate lender releases. Include their compensation and the time required. An investor who has successfully owned apartments may still need specialist support for a restaurant buildout or an industrial environmental issue.

Establish spending authority and escalation rules before a problem arises. If a tenant requires an unbudgeted improvement, determine who can approve it, what evidence is required, and whether the loan or partnership requires consent. Model the financial effect before treating the expense as a minor operational choice. Small decisions can accumulate into a different business plan.

Finally, review concentration at the investor’s total portfolio level. Two individually attractive properties might depend on the same employer, tenant category, lender, or refinancing window. Property-level underwriting remains necessary, but it does not establish that the combined investment fits the investor’s liquidity and risk limits. Record those limits in the acquisition decision so a later favorable cap rate does not quietly override them.

The completed package should therefore contain the model, source documents, assumption register, open-items log, and decision memo. It should also identify a person responsible for keeping each part current. That discipline makes the initial research useful through ownership and disposition, when the investor needs to know whether the original thesis still holds.

Preserve the original seller figures beside every adjustment. The reconciliation should explain each difference without erasing the evidence needed to challenge the buyer’s judgment later.

The cited Fannie Mae glossary is the version effective April 30, 2026; its terminology is program-specific and should be reconciled with the applicable product and current loan documents.