| Primary address | 9 William Avenue, Islip |
| Zip code | 11751 |
| County | Suffolk |
| Municipality | Islip |
| Parcel ID | 345-1-1 |
View detailed information on past sales, title documents and property taxes, including the assessed market value, in their dedicated tabs.
| Current property tax | $12,577 |
| Building class | Two Family Year-Round Residence (220) |
| Acreage | 0.14 |
| Units | 2 |
| Zoning district | Register |
| School district | 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 $42,700, the tax amount paid for 9 William Avenue, Islip, NY 11751 is $13,477.
How many residential units does this building have?This building has 2 residential unit(s).
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 9 William Avenue, Islip, including title documents, transfer conditions, mortgages and liens.
Access detailed property tax data for 9 William Avenue, Islip, NY 11751. Tax information included: property tax, market value and assessed value, exemptions, abatements, and assessment history.
| Tax year | 2025-2026 |
| Base tax | $13,478 |
| Current property tax | $12,577 |
| Market value | $601,409 |
| Assessed value | $42,700 |
Here's the assessment & property tax history for 9 William Avenue, 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 | $601,409 | $42,700 | 30.486 | $13,018 | +3.73% |
| 2023-2024 | $586,538 | $42,700 | 29.39 | $12,550 | +1.68% |
| 2022-2023 | $515,700 | $42,700 | 28.904 | $12,342 | +0.07% |
| 2021-2022 | $460,129 | $42,700 | 28.884 | $12,333 | +3.07% |
| 2020-2021 | $440,206 | $42,700 | 28.023 | $11,966 | -26.94% |
The complete history of permits filed for 9 William Avenue, 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 9 William Avenue, 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 9 William Avenue, 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) |
|---|---|---|---|---|---|
| Wing Elementary School | NR | Public | K-1 | 379 | 0.27 |
| Commack Road Elementary School | 3 | Public | 2-5 | 397 | 0.78 |
| St Mary School | NR | Private | PK-8 | 413 | 0.92 |
| St Mary School | NR | Private | PK-8 | 413 | 0.92 |
| Maud S Sherwood Elementary School | 6 | Public | 2-5 | 335 | 1.29 |
| Name | Rating | Type | Grade range | No of students | Distance to school (mi) |
|---|---|---|---|---|---|
| Islip Middle School | 4 | Public | 6-8 | 641 | 0.87 |
| St Mary School | NR | Private | PK-8 | 413 | 0.92 |
| St Patrick School | NR | Private | PK-8 | 534 | 1.61 |
| East Islip Middle School | 6 | Public | 6-8 | 804 | 1.71 |
| Bay Shore Middle School | 5 | Public | 6-8 | 1,298 | 2.21 |
| Name | Rating | Type | Grade range | No of students | Distance to school (mi) |
|---|---|---|---|---|---|
| Islip High School | 9 | Public | 9-12 | 892 | 0.80 |
| East Islip High School | 8 | Public | 9-12 | 1,145 | 1.74 |
| Bay Shore Senior High School | 5 | Public | 9-12 | 1,910 | 2.32 |
| MDQ Academy | NR | Private | PK-12 | 412 | 3.01 |
| Brentwood High School | 3 | Public | 9-12 | 4,641 | 3.43 |
Data provided by GreatSchools.org © 2025. All rights reserved.
Here are the neighbors for 9 William Avenue, Islip.
| Address | Square feet | Purchase date | Purchase price |
|---|---|---|---|
| 370 Moffitt Blvd, Islip | 01/29/2016 | ||
| 378 Moffitt Blvd, Islip | |||
| 143 Nassau Ave, Islip | |||
| 34 Columbia St, Islip | 1,755 | 10/20/2017 | |
| 40 Columbia St, Islip | |||
| 105 Grant Ave, Islip | |||
| 168 Islip Ave, Islip | |||
| 24 Jenkins St, Islip | |||
| 81 Locust Ave, Islip | 01/25/2018 | ||
| 31 Watson Pl, Islip | |||
| 139 Nassau Ave, Islip | |||
| 85 Locust Ave, Islip | |||
| 350 Moffitt Blvd, Islip | 5,560 | ||
| 26 Jenkins St, Islip | |||
| 390 Moffitt Blvd, Islip | 7,884 | 12/02/2022 | $895,000 |
| 23 Columbia St, Islip | 06/21/2023 | ||
| 26 Columbia St, Islip | |||
| 15 Columbia St, Islip | 11/07/2014 | ||
| 147 A Nassau Ave, Islip | 05/07/2010 | $226,600 | |
| 78 Nassau Ave, Islip | 09/14/2022 | $560,000 |