One operating system for four simultaneous jobs: find visible condo distortions, reconstruct hidden co-op taxes, explain why the anomalies exist, and underwrite the strategies they unlock.
This is not a longer report. Each lane produces a decision artifact: a shortlist, a reconstructed number, a causal explanation, or an underwriting result. Move linearly—or jump straight to the missing answer.
Screen live condo signals by tax ratio, tax share of carry, residual cost, and known friction.
Output · ranked dossiers ↘Reject land leases, eliminate impossible candidates, then reconstruct the missing property-tax field.
Output · evidence grade ↘See how rental-equivalent valuation, unit allocation, benefits, timing, and price distress create the ratio.
Output · causal model ↘Compare the apartment play with an owner-occupied two- or three-family rental strategy.
Output · strategy map ↘A high tax ratio is only a signal. The actual edge is the amount of fixed carry that disappears—without importing legal-use, assessment, building, or resale problems that do not.
This is the high-value AI lane. StreetEasy exposes maintenance, not its tax component. The workflow first eliminates impossibilities, then proves land ownership, then reconstructs the shareholder’s property-tax allocation with an evidence grade.
Ground rent survives a personal property-tax exemption. A leased-land co-op is rejected—not merely discounted.
Do not call this a target until title records and financial statements both clear the gate.
Because property tax cannot exceed total maintenance, this upper-bound test rejects most co-ops without asking a broker for anything.
Use when you have the building’s net real-estate-tax expense and confirmed apartment/total shares.
Use the annual letter only after separating real-estate tax from the shareholder’s allocated underlying-mortgage interest.
Maintenance upper bound, tax intensity, or historical clues. Useful for triage—not for claiming a tax ratio.
Building tax expense plus confirmed apartment and total shares. Narrow enough to rank and request documents.
Current shareholder tax letter separating real-estate tax from underlying-mortgage interest.
“Prewar, converted, few units” is a useful clue—not a complete cause. The ratio emerges from a rental-building assessment model, a unit allocation, timing rules and benefits, divided by today’s resale price.
Small Class 2 properties use a simplified gross-income-multiplier approach and benefit from annual/five-year assessment caps.
The tax burden can look extreme even without a new tax shock: the assessment numerator stays sticky while a hard-to-finance, awkward, or distressed unit reprices downward.
NYC does not simply tax a new condo at projected sellout value. It first estimates what the parcel would be worth as an income-producing rental property: a simplified method for ten units or fewer, and an income-and-expense capitalization method for larger buildings.
Few-unit prewar buildings can generate odd allocations, but a real anomaly usually needs another ingredient: heavy unit interest, physical changes, expired benefits, or a resale price that fell faster than the assessment.
The apartment anomaly is not necessarily the highest-leverage use of the exemption. An owner-occupied two- or three-family property may pair the tax shield with rental income—while a four-plus-unit building likely does not offer the same whole-parcel treatment.
Live in one unit; collect rent from the others; investigate whether the residential parcel receives whole-structure treatment.
Use AI to reconstruct the missing tax field and rank by residual maintenance—not headline maintenance.
Easy to discover; harder to separate a genuine tax distortion from a building or unit-level trap.
Published state guidance suggests only the owner’s residential unit—not the entire larger building—would qualify.
This is a screening model, not a legal conclusion or mortgage underwriting.
At the selected assumptions, the tax benefit adds a probability-weighted $18,200 per year before financing. Confirm whole-parcel treatment under the new provision before underwriting.
The seller does not own Bashi’s private tax shield. Value the ordinary property first, add only probability-weighted personal value, and reserve separately for every defect that survives the exemption.
The model discounts both legal implementation and personal approval. It does not include resale penalties, transaction costs, mortgage effects, or legal defects.
The signal is interesting, but the evidence and downside case are not yet strong enough to advance.
Enter a listing to create a structured research request.
Generate a disciplined prompt covering price, carry, building risk, legal use, comps, title, taxes, and a clear next action.
Ask for the exact tax letter, share allocation, fee ownership, ground-rent status, debt, PILOTs, and assessments.
Convert ordinary-buyer value, probability-weighted personal benefit, and defect reserves into a negotiation range.
The investment thesis still has two gates: local NYC adoption of the optional full exemption and approval of Bashi’s documentation. This site treats both as explicit probabilities rather than facts embedded in a bid.