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Owner-reported income is the only input.
An assessment rests on numbers the owner has every reason to shade.
For Tax Assessors · CompStak One Connect
Assess on the market, not the owner’s income statement.
Owners report the rents that keep assessments low. CompStak shows the rents comparable space actually achieved, with analyst-reviewed comps to back the value on appeal.
Trusted by the leaders in commercial real estate
What assessors miss without verified comps.
Appeals challenge your evidence.
A comp without a verification trail is the first thing counsel attacks.
Fast markets outrun lagged data.
Public records land a year behind the leases that set today’s rents.
CompStak One Connect answers each of these with verified, analyst-reviewed comps.
Get StartedAssessment values, checked against comps that closed.
Rent Predictor and Agent Connect are available on CompStak One Connect.
Validate assessments with market evidence.
Set accurate values across property types and building classes for mass appraisal, using verified lease and sale comps, cap rates, and NOI detail.
Get StartedComp search · by class
Office · Class A · Gotham CBD
Comps28
Median NER$75.50
Median PSF$679.03
Cap rate5.10%
PropertyTypeClassNER
400 Mandel StreetOfficeA$75.50
250 Comp PlazaOfficeA$70.20
1 Stak TowerOfficeA$79.40
Value space with no lease on file.
Describe a space in Rent Predictor and get the Estimated Starting Rent Today with the comps behind it, so vacant and owner-occupied space is not assessed on guesswork.
Get StartedRent Predictor · model input
Subject space · no lease on file
Est. starting rent today$82.00
Range$78.00–$86.00
Comps used14
Underwritten$80.00
CompSFStartingNER
Belobrovka Analytics42,000$82.00$75.50
Comp Advisory Group18,400$79.50$73.10
Stak Capital Partners25,000$84.00$77.25
Run the analysis where your team already works.
Query CompStak comps from ChatGPT, Claude, Gemini, or Copilot through the Agent Connect MCP server, and join them against your own records. Statistics and trends are free; pulling the underlying records counts toward your weekly comp limit.
Get Started“Check this owner-reported rent roll against leases signed in the same class and submarket.”
3 of 6 reported rents sit above the comp set. Estimated Starting Rent Today is $82.00/SF against a reported $88.40.
TenantReportedMarketGap
Belobrovka Analytics$88.40$82.00+$6.40
Comp Advisory Group$79.50$79.50—
Ask for the assessment comps in your own words.
Agent Connect puts CompStak inside Claude, ChatGPT, Gemini, and Copilot. Ask the way you’d ask an analyst, and the work comes back with its source comps attached.
“Check the owner’s reported rent roll for Willis Tower against the leases CompStak has for the building and flag the differences.”
Returns
Rent roll check
“Build market rent and cap rate benchmarks for Class A office in the Camelback Corridor for this assessment cycle.”
Returns
Benchmark table
“Assemble sale comps in Seattle since 2024, with sale price, cap rate, NOI, and True Buyer, for the appeal file.”
Returns
Sale comp table
“Summarize how starting and effective rents for industrial in the Inland Empire moved since the last cycle.”
Returns
Trend + chart
Every field an assessor needs to value a property.
Access verified lease, sale, loan, and property data across major CRE asset types in 105 markets, with the details to analyze markets, value assets, and underwrite opportunities.
Net Effective Rent
Free Rent
Escalations
Tenant Improvements
+ more
Cap Rate
NOI
Price PSF
Buyer & Seller
+ more
Building Class
Size & Floor
Year Built
Landlord
+ more
Lender
Maturity Date
Origination
Loan-to-Value
+ more
Across the asset types you work with:
Office
Retail
Industrial
Multifamily*
Flex
R&D
Land*Multifamily data powered by RealPage
Every comp goes through a rigorous verification process.
Each comp goes through a multi-step data verification process.
400 Mandel Street, Gotham, NY
Belobrovka Analytics · Office
SizeRentTerm
400 Mandel Street, Gotham, NY
Belobrovka Analytics · Office
SizeRentTermNet effective
Verified memberReviewed on intake
One building resolvedEvery party matched
1400 Mandel Industrial PkwyHeld for review
Deal participantsProperty record
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Community Sourcing
40,000+ verified CRE professionals at brokerage and appraisal firms submit comps daily. Transaction data is received and reviewed multiple times.
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AI & Machine Learning
Machine learning and statistical anomaly detection flag figures outside the expected range for the market and building. CRE Ontology resolves the address to one building and matches every party on the deal to a verified entity. Flagged records are held for review.
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Analyst Verification
Our team of CRE research analysts review and verify data daily. They cross-check each transaction against deal participants and property records. Data is never estimated or blindly added to the system.
How other CRE teams use CompStak.
Questions about CRE data for assessors.
How do assessors check owner-reported income?
Against verified lease comps for comparable space. CompStak records net effective rent, free rent, landlord work, and lease terms from the professionals who closed the deals, so reported figures can be tested against the market.
What data supports an income-approach assessment?
Net effective rent and concession detail on the lease side, and sale price, price per square foot, cap rate, and NOI on the sale side, across property type and building class.
How does CompStak verify its comps?
Every comp is processed by a multi-step data verification system, including machine learning algorithms, statistical anomaly detection, and a team of CRE data analysts. Read more about our data standard.
What does CompStak One Connect add for assessment teams?
Rent Predictor, which values space with no lease on file, and Agent Connect, which builds benchmarks and answers questions inside Claude, ChatGPT, Gemini, or Copilot.
How much CRE data does CompStak have?
CompStak has collected 4M+ versions of lease and sale comps across 105 US markets, contributed by more than 40,000 verified CRE professionals and reviewed by CompStak’s analyst team.