The source
The data is the DOF supplemental market value roll, fiscal year 2027, July 24, 2026 vintage, published on the DOF property assessments page. It comes as two files:
| File | Records | Contents |
|---|---|---|
| Condo and co-op file (tax class 2) | 275,091 | Condo lots and co-op units, each with its DOF market value |
| House file (tax class 1) | 684,619 | One-, two- and three-family houses, each with its DOF market value per lot |
Together the two files hold about 960,000 records.
Each record carries a borough, block and lot, a building class, a street address, an apartment number where one applies, a ZIP code, co-op and condo identifiers, and the market value (FMV). We load those fields and nothing else about the property.
What we discard
The DOF roll also lists an owner name on each record. We discard that column at the first step of reading the file. It is never saved to a database, never cached and never shown on any page. On residential lots those names belong to private individuals, and a market value lookup does not need them.
Houses get an extra rule. A house record is never listed at address level on a public page. A homeowner can look up their own address and see their own value, and everyone else sees houses only as totals by neighborhood and borough.
Look up a unit and see the method at work.
Enter an address and apartment number and the lookup returns the DOF market value, the band and the Phase 1 annual figure, using the rules above.
Milton Coste | Licensed Real Estate Associate Broker | Keller Williams NYC | 917.416.7433
How we read the surcharge
Each unit’s market value is compared to the Phase 1 thresholds: $1,000,000 for condos and co-ops and $5,000,000 for houses. The band rate is applied to the unit’s full market value, not only to the part above the floor, and a value exactly on a floor takes the higher rate. That is how DOF presents the schedule: “or greater, but less than” the next band. The rates are on the rates and deadlines page.
Phase 2 is shown as a sensitivity, not a forecast. From July 1, 2028 the statute moves condos and co-ops to the $5,000,000 threshold under a DOF assessed-value system that has not been finalized, so we flag how a unit could change without presenting a 2028 number as settled.
What this data cannot tell you
- Whether a unit is anyone’s primary residence. The roll has no occupancy information. A high DOF value shows exposure, not liability.
- Whether a unit will receive a DOF letter. DOF says the vast majority of listed properties will not.
- The outcome of any exemption application. DOF decides, and a denial can be appealed to the NYC Tax Commission.
- Anything after July 24, 2026. The figures stay at that vintage until DOF publishes a new roll.
Neighborhoods, downloads and corrections
Units are grouped into the neighborhoods used in our market reports, not by ZIP code. Aggregate files are described on the data page. If a figure on this site does not match the DOF roll, email milton@miltoncoste.com with the address and I will check it against the source file.
Questions people ask
Where does the pied-a-terre tax lookup data come from?
It comes from the NYC Department of Finance supplemental market value roll for fiscal year 2027, published July 24, 2026.
Does the site publish owner names?
No. The owner column in the DOF roll is discarded when the file is read and is never stored or shown.
Why are individual houses not listed by address?
House records belong to private homeowners. Houses appear publicly only as totals by neighborhood and borough, and an owner can look up their own address.
Ready to see your own number?
The lookup is free and shows the figure on screen first. If you want to talk through keeping, leasing or selling, call or message me.
Milton Coste | Licensed Real Estate Associate Broker | Keller Williams NYC | 917.416.7433
More on the NYC pied-a-terre tax
This page is educational and is not legal or tax advice. Rates, thresholds and dates come from NY Tax Law Article 30-C (text of the statute) and the NYC Department of Finance (non-primary residence surcharge page), checked October 9, 2026. Confirm your own situation with a New York attorney or your accountant. Milton Coste, Licensed Real Estate Associate Broker, Keller Williams NYC, 360 Madison Avenue, 9th Floor, New York, NY 10017.