How Do I Evaluate a Commercial Property’s Income Potential?

The six-step income evaluation, in order

Every institutional underwriter runs some version of this sequence. Do it in order — each step feeds the next.

1. Audit the rent roll — obtain every signed lease and amendment, and rebuild the rent roll from the documents: base rents, escalations, expirations, options, concessions, arrears, and security deposits. Flag any tenant paying materially above market.
2. Benchmark market rents — compare each in-place rent to current asking and taking rents for comparable space in the same submarket, so you know which leases are upside and which are risk at rollover.
3. Apply vacancy and credit loss — deduct 3–5% of gross income even on full buildings, then model each lease expiring within 36 months explicitly: probability of renewal, months of downtime, free rent, and re-leasing costs.
4. Rebuild the expenses — construct the expense load from source documents: actual tax bills, insurance quotes, utility history, payroll, and contracts. Add reserves ($0.25–$0.50/SF minimum) and management fees even if self-managing.
5. Derive NOI — effective gross income minus operating expenses, excluding debt service and depreciation. Compute it twice: in-place NOI from today’s facts and stabilized NOI from defensible assumptions, and know exactly which one a quoted price is based on.
6. Convert to value and return — apply submarket cap rates to both NOI figures, then layer financing to compute cash-on-cash and multi-year IRR. Buy only when in-place, stabilized, and levered metrics all clear your hurdle.

Run the arithmetic with the NOI calculator and the cap rate calculator — and keep the in-place and stabilized cases in separate columns. Deals go bad when buyers pay a stabilized price for in-place performance.

Step one in practice: the rent roll is a claim, not a fact

The rent roll a seller hands you is a summary of what the seller says the leases say. Verification means reading the leases themselves — every one, with every amendment and side letter — and then testing the documents against reality: 12–24 months of actual collections, arrears schedules, and at contract stage, tenant estoppels confirming the terms. The recurring NYC findings: escalations recorded incorrectly, free-rent periods still burning off, side agreements reducing effective rent, month-to-month tenants listed at expired lease rents, and arrears quietly netted out of the summary. In rent-regulated multifamily, add a DHCR rent history pull for every stabilized unit — overcharge exposure survives the sale and lands on the buyer. The rent stabilization guide covers that verification layer.

Market rents and the vacancy assumption

Benchmarking in-place rents against market answers the question that drives value: is the income durable, growing, or at risk? A building 15% under market is embedded upside that arrives at each rollover; a building 15% over market is a rent roll that shrinks on paper the day you buy it. In NYC the benchmark must be submarket- and class-specific — Midtown South Class B office rents tell you nothing about a Village retail strip — and it must use taking rents (what deals actually sign at, net of concessions), not asking rents.

Vacancy and credit loss is where optimistic underwriting hides. A 100%-occupied building is not a 0%-vacancy building over any hold period: apply 3–5% as a baseline, then model each near-term expiration explicitly — NYC office re-leasing downtime commonly runs 6–12 months, retail 12–24. Foot-traffic-dependent assets deserve their own demand check; see how to evaluate foot traffic and location.

The NYC expense traps that wreck pro formas

Two expense lines sink more NYC underwriting than all others combined. First, real estate taxes: the seller's current tax bill reflects the current assessment, and both a sale at a higher value and the expiry of any abatement (421-a, ICAP, J-51) can reset taxes sharply upward. Underwrite the tax line you will pay, not the one the seller pays — our NYC property tax guide for investors walks the assessment mechanics. Second, Local Law 97: buildings over 25,000 SF face emissions caps that tightened in 2030-cycle projections, and pre-1980 stock frequently needs six- or seven-figure retrofit capital to avoid annual penalties. Add insurance — up double digits annually in recent years — and underfunded reserves, and a clean-looking expense ratio can move five points between marketing setup and audited reality.

From NOI to value: cap rate, cash-on-cash, and sanity checks

NOI becomes value through the cap rate — but the cap rate must match the NOI. In-place NOI divided by the asking price gives the true going-in yield; if a seller quotes a cap rate on stabilized or pro forma NOI, reprice it on in-place numbers before comparing to market. 2026 NYC benchmarks run roughly 4.5%–5.5% for free-market Manhattan multifamily, 5.5%–7%+ for heavily stabilized product, 5%–6.5% for neighborhood retail, and wider for Class B office — the full framework is in NYC cap rates explained.

Then check the levered result: at 2026 debt costs, many low-cap-rate NYC assets are negatively levered on day one, so cash-on-cash in year one may sit below the unlevered yield and the return case rests on rent growth or repositioning. Cross-check value with the income, sales-comparison, and replacement-cost approaches described in NYC commercial property valuation methods and the how to value commercial property guide. For the broader go/no-go decision this analysis feeds, see how to tell if a commercial property is a good investment.

How Skyline approaches income evaluation

Skyline Properties underwrites every asset it brings to market the way the buyer will — in-place NOI from the documents, stabilized NOI from defensible assumptions, and a pricing view built on both. That is the discipline behind our off-market investment sales practice: deals priced on real income close, and Skyline's record — including the $105M sale of 101 Greenwich Street and the $72M sale of 530 West 25th Street — was built on underwriting that survived buyer diligence. Our pricing methodology is public at how we price. If you want your property's income potential evaluated the way institutional buyers will evaluate it, request a confidential Broker Opinion of Value.