20 William Ave
Central Islip, NY 11722
— ba 830 sqft Built 1935 Lot 9,148 sqft single_family
No recorded sales
Location
Timeline: Sale, Listing & Tax History
Recorded events
No recorded events
No sale or listing events are on file for this property.
Tax assessment history
| Year | Building | Land | Total assessed | Tax paid |
|---|---|---|---|---|
| 2025 | $18,750 | $6,900 | $25,650 | $8,633 |
| 2024 | $18,750 | $6,900 | $25,650 | $8,276 |
| 2023 | $18,750 | $6,900 | $25,650 | $8,276 |
| 2022 | $18,750 | $6,900 | $25,650 | $8,183 |
| 2021 | $18,750 | $6,900 | $25,650 | $8,076 |
| 2020 | $18,750 | $6,900 | $25,650 | $8,054 |
| 2018 | $18,750 | $6,900 | $25,650 | $7,939 |
| 2017 | $18,750 | $6,900 | $25,650 | $11,178 |
| 2016 | $18,750 | $6,900 | $25,650 | $1,594 |
| 2015 | $18,750 | $6,900 | $25,650 | $1,591 |
| 2014 | $18,750 | $6,900 | $25,650 | $1,594 |
| 2013 | $18,750 | $6,900 | $25,650 | $1,561 |
| 2012 | $18,750 | $6,900 | $25,650 | $1,560 |
| 2011 | $18,750 | $6,900 | $25,650 | $5,994 |
| 2010 | $18,750 | $6,900 | $25,650 | $5,775 |
| 2008 | $18,750 | $6,900 | $25,650 | $5,340 |
Property facts
Year built
1935
Property type
single_family
Stories
—
Beds
—
Baths
—
Living area
830 sqft
Lot size
9,148 sqft
ZIP code
11722
City
Central Islip
Street
William Ave
Coordinates
40.79441, -73.20125
Comparable properties nearby
Block-level micro-comps
Same street, ±3 house numbers, sold in the last 24 monthsFrequently asked questions
When did 20 William Ave last sell?
No public-record sale is on file for 20 William Ave.
What is the current tax assessment for 20 William Ave?
The most recent total assessment for 20 William Ave (year 2025) is $25,650 with $8,633 in property tax.
When was 20 William Ave built?
20 William Ave was built in 1935.
How does 20 William Ave compare to others on William Ave?
We track 4 other properties on William Ave. Browse the list under "Other properties on William Ave" to compare beds, baths, and sale history.
What are the property facts for 20 William Ave?
20 William Ave is a — bath, 830 sqft, 9,148 sqft lot single_family.
Is 20 William Ave a flip candidate?
No — 20 William Ave does not appear in our flips dataset.
Is 20 William Ave a tax-appeal candidate?
No — 20 William Ave is not currently flagged as a tax-appeal candidate.
Forecast for this area
ZIP-area linear projection — not a per-property automated valuationQuarterly trend
-2.9%
Implied 1-yr
-11.7%
2026 Q1
$467.5K
2026 Q2
$450.6K
ZIP 11722 — Median Price History + Forecast
Explore nearby
Geography
Other properties on William Ave