421 Union Ave, Mamaroneck, NY 10543 Property Records

Westchester County and Rye Town property record for 421 Union Ave, Mamaroneck, NY 10543

Property Summary

Property Type	Triplex
Details	5 bd · 3 ba · 2,286 sqft · built 1910
Lot Size	0.164 acres (7,141 sqft)
Owner	2 Individual Names on File
Tax Bill	$19,919 (2026)
Deeds & Mortgages	Jul 2026 Sale
Flood Zone	Zone X (minimal risk)
APN	`554803 154.42-1-42`

Property Details

APN / Parcel Number

Primary APN	`554803 154.42-1-42`
Alternative APNs	`480315404200010420000000` `00005954000`

Interior

Bedrooms	5 Beds
Full Baths	3 Baths
Total Rooms	11 Rooms
Stories	2 Stories
Building Area	2,286 sqft Total Area
1st Floor Area	909 sqft
2nd Floor Area	909 sqft
Upper Floors Area	336 sqft
Attic	Attic
Attic Area	336 sqft
Game Room	Game Room
Fireplaces	1 Fireplace
Fireplace	Fireplace

Exterior

Year Built	Built 1910
Effective Year Built	Effective 1990
Architectural Style	Traditional
Exterior Material	Composition/Composite
Lot Area	7,141 sqft (0.164 acres)
Lot Dimensions	198 ft deep x 35 ft wide

Exterior Amenities

Porch	Slab
Porch Area	352 sqft
Shed	1 Shed
Shed Area	132 sqft

Utilities, Heating & Cooling

Heating System	Hot Water
Heating Fuel	Gas
Sewer	Municipal
Water Source	Commercial

Location & Zoning

Account Number	00005954000
Street Address	421 UNION AVE
City	MAMARONECK
State	NY
Zip	10543-2634
Property Category	Residential
Property Type	Residential > Multi-Unit > Triplex
Local Zoning Code	03 - MULTI
Legal Block	1
Legal Lot Number	42.000
Jurisdiction	WESTCHESTER NY
Township / Civil Division	RYE
Census Block Group	3
Census Block	3015
Census Tract	7401

Owner

Source: Westchester County and Rye Town records, as of October 21, 2026

Owner names and exact recorded amounts are on file and can be viewed instantly on this page with a free 10-day trial.

Owner of Record	2 Individual Names on File
Mailing Address	421 UNION AVE, MAMARONECK, NY 10543-2634
Occupancy	Owner Occupied
Owner Type	Individual
Vesting	Tenants in Common

Deeds, Mortgages & Sale History

Assessor's Deed Record

Deed Names	2 Names on Deed
Record Updated	Oct 29, 2026

July 2026: Bargain and Sale Deed, Transfer

Document Type	Bargain and Sale Deed
Jurisdiction	WESTCHESTER NY
Recording Date	Jul 7, 2026
Property Address	421 UNION AVE, MAMARONECK, NY 10543-2634
Document Number	0000003006
Instrument Date	Dec 3, 2025
Instrument	20263006
Transaction Type	Transfer
Record Updated	Jul 14, 2026
Title Company	FIDELITY NATIONAL TITLE, FIDELITY NATIONAL TITLE INSURA

Transaction

Tax	$0.00
Amount Accuracy	Full Amount Stated
Additional	Arm's Length

Transferred From (Grantor/Seller)

Name	Verified Name

Transferred To (Grantee/Buyer)

Name	Verified Name
Relationship	Tenants in Common
Address	421 UNION AVE, MAMARONECK, NY 10543-2634

Tax Assessment & Valuation

Source: Westchester County and Rye Town assessment roll, as of May 14, 2026

Property Jurisdictions

Type	Name
State	New York
County	Westchester County
County Subdivision	Rye Town
Municipality	Mamaroneck Village
Unified School District	Rye Neck Union Free School District (KG - 12)

Tax Bill & Assessment History

Year	Tax Bill	Assessed Value	Assessed Market Value
2026	$19,919.00 (+37.78%)
2025	$14,457.00	$878,700 (+8.67%) Land $393,900 Building $484,800	$878,700 (+8.67%) Land $393,900 Building $484,800
2024		$808,600 (+10.36%) Land $393,900 Building $414,700	$808,600 (+10.36%) Land $393,900 Building $414,700
2023		$732,700 Land $375,100 Building $357,600	$732,700 Land $375,100 Building $357,600

Assessed value and assessed market value are set for property tax purposes and are not market price estimates.

Flood

Source: FEMA National Flood Hazard Layer, effective September 18, 2026 · OpenFEMA NFIP redacted claims and policies, as of September 2026

FEMA Flood Zone	Zone X minimal risk
Nearest Special Flood Hazard Area	Zone AE, within 500 ft
Flood Insurance Requirement	Not required lenders may require it
Flood Insurance Cost	Premium on File median of 17 policies
Community Rating System	Class 8 (10% premium discount)
Nearby Flood Policies	17 in force
Nearby Flood Claims	41 (1978–2023)
Claims Outside the SFHA	30 of 41
Most Recent Claim	Sep 2023 · Severe Storm And Flooding
Claims by Event	Remnants Of Hurricane Ida, Sep 2021 · 5 claims Hurricane Irene, Aug 2011 · 5 claims Severe Storms And Inland And Coastal Flooding, Apr 2007 · 5 claims

Values are read at the parcel center point; flood claims are located to the census block group, not this parcel; lenders make the official flood determination.

Wildfire

Source: USDA Forest Service Wildfire Risk to Communities (2nd edition), as of 2024

Wildfire Risk	Not rated no burnable land within ember reach

Values cover an area roughly 900 ft across, not the parcel itself; insurers use their own ratings.

Drinking Water

Source: EPA Safe Drinking Water Information System, as of September 2026

Water System	WESTCHESTER JOINT WATER WORKS serves 59,629 people · EPA ID NY5903435
Water Source	Surface water
Last State Inspection	Mar 2025
Lead	3 ppb (2026–2028) action level 15 ppb

Violations Reported to EPA

Water Quality	Failure to filter currently in violation since Jun 1993 Haloacetic acids resolved · Jul 2019
Treatment and Procedure	None last 10 years
Monitoring and Reporting	None last 3 years

Results are for the whole water system, not water tested at this address; lead at the tap also depends on the building's own pipes.

Internet Providers

Source: FCC Broadband Data Collection, based on 673 locations within half a mile, as of December 31, 2025

Provider	Max Down / Up (Mbps)
Optimum Fiber · Cable	8,000 / 8,000
Verizon Fiber · Fixed Wireless in parts of the area	980 / 880
T-Mobile Fixed Wireless	100 / 20