| Primary address | 21 William Avenue, East Islip |
| Zip code | 11730 |
| County | Suffolk |
| Municipality | Islip |
| Parcel ID | 372-4-20 |
View detailed information on past sales, title documents and property taxes, including the assessed market value, in their dedicated tabs.
| Sale date | 09/06/2005 |
| Sale price | $280,000 |
| Arm's length | Register |
| Current property tax | $7,883 |
| Building class | One Family Year-Round Residence (210) |
| Acreage | 0.25 |
| Zoning district | Register |
| School district | East Islip |
View more neighborhood information such as transportation, nearby schools and risk designations in the dedicated tab.
Property reports include comprehensive occupancy, improvement and development information (where available).
Create a free account to access valuable data points such as:
Assessed at $31,000, the tax amount paid for 21 William Avenue, East Islip, NY 11730 is $8,666.
When was 21 William Avenue, East Islip, NY 11730 last sold and what was the last sale price?21 William Avenue, East Islip, NY 11730 was last sold in 09/06/2005 for $280,000.
View detailed property contacts like owners, building management, representatives from permits and tenants with a free account.
Create a free account to view the complete sales history for 21 William Avenue, East Islip, including title documents, transfer conditions, mortgages and liens.
| Purchase date | Purchase price | Buyer name | Seller name |
|---|---|---|---|
| 09/06/2005 | $280,000 | Register | Register |
To view the complete history of deeds, mortgages, assignments of leases and rents, and more, sign up for free. Available data goes back to 1966.
R: Recorded date
D: Document date
Access detailed property tax data for 21 William Avenue, East Islip, NY 11730. Tax information included: property tax, market value and assessed value, exemptions, abatements, and assessment history.
| Tax year | 2025-2026 |
| Base tax | $8,667 |
| Current property tax | $7,883 |
| Market value | $436,620 |
| Assessed value | $31,000 |
Here's the assessment & property tax history for 21 William Avenue, East Islip, including the evolution of the total tax rate and corresponding property tax.
| Year | Market value | Assessment value | Total tax rate | Property tax | Year over year change |
|---|---|---|---|---|---|
| 2024-2025 | $436,620 | $31,000 | 26.849 | $8,323 | +2.69% |
| 2023-2024 | $425,824 | $31,000 | 26.145 | $8,105 | +0.84% |
| 2022-2023 | $374,396 | $31,000 | 25.927 | $8,037 | -0.72% |
| 2021-2022 | $334,052 | $31,000 | 26.114 | $8,095 | +2.36% |
| 2020-2021 | $319,588 | $31,000 | 25.513 | $7,909 | -20.34% |
The complete history of permits filed for 21 William Avenue, East Islip, including new construction or demolition permits, plus any work pertaining to plumbing, heating and sprinkler systems is available with a free account. Available data goes back to 1990.
Create a free account to unlock extended information for 21 William Avenue, East Islip, including whether it's located in FEMA flood zones, floodways or special flood hazard areas, as well as the Coastal barriers resources system area (COBRA).
| FEMA flood zone(s) | X (See more on map) |
Access the detailed traffic volume map for 21 William Avenue, East Islip to see estimated average daily traffic on streets surrounding the property as well as the types of properties in its vicinity.
| View daily traffic map |
| Name | Rating | Type | Grade range | No of students | Distance to school (mi) |
|---|---|---|---|---|---|
| St Mary School | NR | Private | PK-8 | 413 | 0.14 |
| St Mary School | NR | Private | PK-8 | 413 | 0.14 |
| John F Kennedy Elementary School | 5 | Public | 3-5 | 450 | 0.47 |
| Chatterbox Day School | NR | Private | PK-1 | 61 | 0.98 |
| Chatterbox Day School | NR | Private | PK-1 | 61 | 0.98 |
| Name | Rating | Type | Grade range | No of students | Distance to school (mi) |
|---|---|---|---|---|---|
| St Mary School | NR | Private | PK-8 | 413 | 0.14 |
| East Islip Middle School | 6 | Public | 6-8 | 804 | 1.53 |
| Islip Middle School | 4 | Public | 6-8 | 641 | 1.54 |
| St Patrick School | NR | Private | PK-8 | 534 | 2.54 |
| Bay Shore Middle School | 5 | Public | 6-8 | 1,298 | 3.18 |
| Name | Rating | Type | Grade range | No of students | Distance to school (mi) |
|---|---|---|---|---|---|
| Islip High School | 9 | Public | 9-12 | 892 | 1.53 |
| East Islip High School | 8 | Public | 9-12 | 1,145 | 1.62 |
| Bay Shore Senior High School | 5 | Public | 9-12 | 1,910 | 3.17 |
| Connetquot Alternative Preschool At Premm | NR | Public | 0 | 3.59 | |
| MDQ Academy | NR | Private | PK-12 | 412 | 3.99 |
Data provided by GreatSchools.org © 2025. All rights reserved.
Here are the neighbors for 21 William Avenue, East Islip.
| Address | Square feet | Purchase date | Purchase price |
|---|---|---|---|
| 172 Suffolk Ave, Brentwood | 02/22/2016 | $120,000 | |
| 246 Commack Rd, Islip | 1,300 | 02/23/2024 | $583,500 |
| 349 Silva St, Holbrook | 01/25/2012 | $328,750 | |
| 67 Otis Rd, Islip Terrace | 03/30/2007 | $399,500 | |
| 551 Marseille Path, Sayville | 08/25/2005 | $622,500 | |
| 36 Lawrence Ln, Bay Shore | 07/12/2011 | ||
| 38 Church St, Central Islip | 1,875 | 12/02/2019 | $290,000 |
| 6 McGrath St, Central Islip | 1,704 | 10/26/2020 | $340,000 |
| 27 Norman Dr, Bohemia | 08/31/2005 | $515,000 | |
| 921 Lowell Ave, Central Islip | 05/10/2011 | $115,000 | |
| 220 Norwood St, Islip Terrace | 12/28/2023 | $595,000 | |
| 30 13th St, Holbrook | 08/04/2005 | $469,000 | |
| 79 Sperry CT, Brentwood | 09/08/2005 | $379,899 | |
| 277 Maple St, Islip | 10/21/2011 | $325,000 | |
| 86 Nassau St, Islip Terrace | 08/25/2010 | $282,000 | |
| 32 Oakridge Dr, Bay Shore | 2,034 | 05/05/2020 | |
| 215 New Hampshire Ave, Bay Shore | 07/23/2009 | ||
| 209 Bryant St, Islip Terrace | 1,212 | 03/21/2018 | $419,210 |
| 11 Twin CT, Sayville | 2,020 | 01/22/2021 | $590,000 |
| 15 Meadow Dr, Bay Shore | 08/31/2005 | $323,500 |