# 420 12th Street, Brooklyn

Co-op · 70 units · built c. 1881 · Block 1098, Lot 1.

On Umarelli: https://umarelli.org/nyc/3010980001/420-12-street

More construction in Park Slope: https://umarelli.org/nyc/brooklyn/park-slope.md

Every lot on block 1098: https://umarelli.org/nyc/brooklyn/1098.md

## Building permits

- Alteration, filed Mar 19, 2026, estimated cost $100K, described as “In apt B1R, construct primary en-suite bathroom including water closet,lavatory, and curbed step-in shower with all assoc. Plumbing and finishes. No change in occupancy use or egress.”
- Alteration, filed Mar 3, 2026, estimated cost $50K, described as “Mechanical modifications to include ac replacement only. No change to existing means of ventilation. No change of use, occupancy or egress”
- Alteration, filed Feb 12, 2026, estimated cost $5K, described as “To file MS work type to Install new HVAC for unit H1R. No change in use, egress or occupancy under this application.”
- Alteration, filed Nov 19, 2025, estimated cost $40K, described as “Mechanical modifications to include ac replacement only. No change to existing means of ventilation. No change of use, occupancy or egress”
- Alteration, filed Oct 30, 2025, estimated cost $28K, described as “Modifications to existing residential space. No change to use, occupancy or egress”
- Alteration, filed Jun 12, 2025, estimated cost $40K, described as “Mechanical modifications to include HVAC replacement and replacement of associated ductwork. No change of use, occupancy or egress”
- Alteration, filed Jun 9, 2025, estimated cost $28K, described as “Modifications to existing residential space. No change to use, occupancy or egress”
- Alteration, filed Jun 6, 2025, estimated cost $40K, described as “Mechanical modifications to include HVAC replacement and replacement of associated ductwork. No change of use, occupancy or egress”
- Alteration, filed Feb 10, 2025, estimated cost $40K, described as “Mechanical modifications to include HVAC replacement and replacement of associated ductwork. No change of use, occupancy or egress”
- Alteration, filed Jan 7, 2025, estimated cost $40K, described as “Mechanical modifications to include HVAC replacement and replacement of associated ductwork. No change of use, occupancy or egress”
- Alteration, filed Oct 8, 2024, estimated cost $40K, described as “Mechanical modifications to include HVAC replacement and replacement of associated ductwork. No change of use, occupancy or egress”
- Alteration, filed Jul 3, 2024, estimated cost $40K, described as “Modifications to existing residential space. No change to use, occupancy or egress”
- Alteration, filed May 16, 2024, estimated cost $80K, described as “Interior cosmetic renovation of duplex apartment 1LR. No change in use, egress, or occupancy.”
- Alteration, filed May 19, 2023, estimated cost $24K, described as “Work involves the demolition and installation of non-structural partitions and new finishes. Relocation and replacement of existing ceiling light fixtures/fans. New rated enclosure through floors 2-4 . No change of use, egress or occupancy”
- Alteration, filed May 17, 2022, estimated cost $26K, described as “Filing for interior work for apartment A3L on 3RD & 4TH floors to remove a non-load bearing wall in kitchen and install drop-soffit to support upper kitchen cabinets. wall and floor tile to be removed and re-installed in the bathroom on…”
- Alteration, filed May 17, 2022, estimated cost $14K, described as “Filing for removal of gas oven range, and modification of existing gas riser in kitchen for apartment A3L on 3rd floor, replacing plumbing fixtures on 4th floor bathroom, no change on location.”
- Alteration, filed May 3, 2021, estimated cost $30K, described as “Renovation of the upper level of duplex apartment #E1L, located on the 2ND floor. Partition work, cabinetry, and finishes. No change to use, occupancy or egress.”

## Property taxes

- Assessment: $7,875,900
- 2026–27 tax: $817,240
- Market value (city estimate): $17,502,000
- Taxable value: $7,668,350
- Assessed land: $958,500
- Assessed improvements: $6,917,400

## Tax breaks

- Co-op and condo abatement, with no end date, a $137,834 credit this tax year.

## Zoning

R6B (part of the lot is R6A): floor area ratio 2.68 built, above the 2.00 base zoning allows, which bonuses, transfers or older rules can permit.

## Recent sales

- Jul 15, 2026: $2,700,000
- Feb 2, 2026: $1,900,000
- Jul 24, 2025: $995,000
- Jul 21, 2025: $2,495,000
- Jun 27, 2025: $1,995,000
- Apr 4, 2025: $2,132,000
- Jan 23, 2025: $2,570,000
- Nov 14, 2024: $1,625,000
- Nov 7, 2024: $2,000,000
- Feb 6, 2024: $1,885,000

The 10 most recent of 40 open-market sales since 2016, from the Department of Finance’s sales files.

## Flood zone

Current FEMA flood map: zone X, minimal flood hazard.

## Landmarks

Part of Park Slope Historic District Extension (Historic District). 28 Landmarks Preservation Commission permits are on file.

From New York City and Jersey City public records, refreshed within a day of each release. Sources: https://umarelli.org/sources. Methodology and corrections: https://umarelli.org/methodology