Where Our Numbers Come From

Data sources

Source	What we use it for
DOF Supplemental Market Value Roll (July 2026; roll date July 24, 2026)	The file the surcharge is administered from: 959,710 records, including DOF's own imputed values for 36,677 co-op units across 764 buildings. Powers the database, neighborhood and borough pages, and co-op unit pricing in reports.
Live DOF assessment roll (NYC Open Data, dataset 8y4t-faws)	Primary source for individual free-check reports: per-unit market and assessed values on the current FY roll, refreshed as DOF updates it.
PLUTO (Dept. of City Planning)	Building identity verification — residential unit counts that confirm which tax lots belong to which building before we price anything.
NY Tax Law Article 30-C, DOF's final rules (adopted July 14, 2026), and DOF's published deadlines	Every rate, threshold, exemption, penalty and date we state.

Calculation rules

• The base is DOF market value — the NOPV "Market Value" line — never assessed value, never sale price.
• Flat rates on the full value. The statute's rate table can be read flat or marginal; our counsel has confirmed the flat reading as the sound, conservative interpretation, and every figure on this site uses it. If DOF ultimately administers the table marginally, actual bills would come in lower than our figures — never higher. Example of the gap: a $3.1M condo is $162,750 flat vs $85,250 marginal.
• Co-ops: DOF's published per-unit value where it exists (764 buildings); otherwise the statutory fractional-share method (building DOF value × ownership %).
• Building pages count residential units only (retail, garage, storage and sub-250-sq-ft lots excluded) and take each lot's final-period roll value.
• Neighborhood and borough pages aggregate the supplemental roll by ZIP code; ZIP boundaries approximate neighborhood borders, so edge blocks may appear in an adjacent area's totals. Known DOF ZIP errors are corrected and noted in our data pipeline.
• "Max annual surcharge" figures are pre-exemption ceilings — the sum if no exposed unit claimed any exemption. Actual collections will be far lower; the Comptroller projects ≈$500M/yr from roughly 11,200 properties, against 24,173 over thresholds on the initial roll.
• Ambiguous classifications (condos on class-1 lots) are marked, and our reports show both possible schedules.

Update cadence

The supplemental roll remains open to correction through December 2026; our copy and every page built from it regenerate when DOF publishes changes. Individual reports always pull the live assessment roll at request time. Guide pages carry a visible "last updated" date and change when the law, DOF guidance, or our data does — not for cosmetics.

What our numbers are not

Everything on this site and in our free reports is an educational estimate built from public records — not a tax bill, not a DOF determination, and not legal, tax or accounting advice. Your official Notice of Property Value and DOF's own correspondence control your actual liability; where our figure and DOF's differ, DOF's governs and we'd like to hear about it. Corrections: piedaterre@conquest.nyc — factual errors get fixed and noted, fast (ask the readers who've caught us).

Questions owners ask

Where does piedaterretax.nyc get its data?

Public records: DOF's Supplemental Market Value Roll (July 2026, 959,710 records — the file the surcharge is administered from), the live DOF assessment roll via NYC Open Data, and PLUTO for building verification. Rates, deadlines and exemptions come from NY Tax Law Article 30-C and DOF's final rules adopted July 14, 2026.

Are the site's surcharge figures official tax determinations?

No — they are educational estimates computed from public records under stated rules (including the counsel-confirmed flat-rate reading, the conservative interpretation). Official liability is determined by DOF; the Notice of Property Value and DOF correspondence govern.

Disclaimer. This page is educational information from Conquest, a licensed New York real estate brokerage. It is not legal, tax, or accounting advice, and no advisory relationship is created by reading it. Deadlines and figures reflect DOF's published rules and roll as of the "last updated" date above.