Data / Nonprofits / Washington / Seattle / Mutual and membership benefit
Mutual and membership benefit nonprofits in Seattle, WA: 40 registered with the IRS
40 mutual and membership benefit nonprofits are registered with the IRS in Seattle, WA, 2 of them 501(c)(3) charities; the 22 that report revenue took in $712.7 million. The largest by revenue: Seiu Healthcare NW Health Benefits Trust ($504.1 million), Oregon Essential Workforce Health Care Fund ($57 million), Portage Bay Insurance ($55.6 million).
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Every organization, largest by revenue first
| Organization | Type | Since | Revenue | Assets | Filing |
|---|
| Seiu Healthcare NW Health Benefits Trust | 501(c)(9) | 2007 | $504.1 million | $588.2 million | 2025-06 |
| Oregon Essential Workforce Health Care Fund | 501(c)(9) | 2023 | $57 million | $102.3 million | 2024-12 |
| Portage Bay Insurance | 501(c)(3) | 2005 | $55.6 million | $187.4 million | 2024-06 |
| Vigilant Manufacturers Trust | 501(c)(9) | 2019 | $18.1 million | $2.1 million | 2025-09 |
| Washington Surveying & Rating Bureau | 501(c)(6) | 2002 | $15.7 million | $12.1 million | 2025-12 |
| Alaska Airlines 501C9 Welfare Trust | 501(c)(9) | 2011 | $14.3 million | $12.9 million | 2024-12 |
| Spokane Fire Firghters Benefit Trust | 501(c)(9) | 2015 | $13.8 million | $43.2 million | 2024-12 |
| Leisure Care Health Benefits Trust | 501(c)(9) | 2022 | $11.7 million | $47,179 | 2025-09 |
| Arizona Technology Council Employee Benefit Trust | 501(c)(9) | 2021 | $9.2 million | $392,678 | 2024-12 |
| Seiu Local 105 Health and Welfare Trust Fund | 501(c)(9) | 2010 | $5.3 million | $1.7 million | 2024-12 |
| Vigilant Manufacturers Trust of Arizona | 501(c)(9) | 2020 | $2.8 million | $58,912 | 2024-12 |
| Seattle Police Offers Guild Benefit Trust | 501(c)(9) | 2014 | $2.1 million | $6 million | 2024-12 |
| Santa Monica Firefighters Health Benefit Trust | 501(c)(9) | 2003 | $1.3 million | $13.1 million | 2024-12 |
| Pacific Northwest Hospitality Training Program | 501(c)(9) | 2019 | $595,191 | $3.3 million | 2024-12 |
| Ethioedir | 501(c)(12) | 2019 | $387,660 | $1.5 million | 2024-12 |
| Alpha Theta Delta Alumni Building Association | 501(c)(7) | 2010 | $352,060 | $3 million | 2024-12 |
| Hawaiian Airlines Inc Pilots Voluntary Employee Beneficiary | 501(c)(9) | 2007 | $150,191 | $48 million | 2024-12 |
| South Bay Hotel Employees Restaurant Employees Legal Fund | 501(c)(9) | 2007 | $84,343 | $1.3 million | 2024-12 |
| Independent Order of Odd Fellows | 501(c)(8) | 1962 | $62,842 | $2.3 million | 2025-04 |
| Sons of Italy in America | 501(c)(8) | 2016 | $50,400 | $169,547 | 2025-06 |
| Green Lake Masonic Association | 501(c)(2) | 2014 | $34,125 | $441,464 | 2025-12 |
| Free & Accepted Masons of Washington | 501(c)(10) | 1941 | $10,028 | $776,936 | 2025-12 |
| Compass and Chart Society | 501(c)(7) | 2025 | $0 | $0 | 2025-06 |
| Crown Hill Business Association | 501(c)(6) | 2014 | $0 | $0 | 2025-12 |
| Homeowners of 1011 North 50TH Street | 501(c)(4) | 2014 | $0 | $0 | 2026-06 |
| Iaff Local 3740 Skyway Fire Fighters Association | 501(c)(5) | 2026 | $0 | $0 | 2025-12 |
| Knights of Columbus | 501(c)(8) | 1940 | $0 | $0 | 2025-12 |
| Knights of Columbus North Seattle C Ouncil 5177 | 501(c)(8) | 2026 | | | |
| Lodge of the Lions Gate | 501(c)(10) | 2005 | $0 | $0 | 2024-12 |
| Newcomers Club of Greater Seattle | 501(c)(7) | 2019 | $0 | $0 | 2025-09 |
| Northwest Council of Airshows | 501(c)(6) | 2025 | $0 | $0 | 2025-12 |
| Potlatch Beach Division No 2 Community Association | 501(c)(12) | 2002 | $0 | $0 | 2025-12 |
| Product Management Consortium | 501(c)(6) | 2014 | $0 | $0 | 2024-12 |
| Seattle Finance Collective | 501(c)(3) | 2020 | $0 | $0 | 2025-12 |
| University of Washington Chapter of the Am Assoc of Univ Professors | 501(c)(6) | 2014 | $0 | $0 | 2025-06 |
| Washington Cannabusiness Association Healthcare Trust | 501(c)(9) | 2025 | | | |
| Washington State Chapter of Asmbs | 501(c)(6) | 2018 | $0 | $0 | 2025-12 |
| Washington State Outdoor Advertisin G Association | 501(c)(6) | 2026 | $0 | $0 | 2025-12 |
| Washington Title Insurance Rating Organization | 501(c)(6) | 2019 | $0 | $0 | 2025-12 |
| Zeta Upsilon Chapter of Omega Psi Phi Fraternity Inc | 501(c)(4) | 2016 | $0 | $0 | 2025-10 |
Other causes in Seattle, WA
Every nonprofit in Seattle, WA · Mutual and membership benefit nonprofits across the state · Nonprofits in every city of the state
Read from the IRS Exempt Organizations Business Master File, updated by the IRS on October 24, 2026 and rebuilt here every morning. Revenue and assets are from each organization's latest filing as the IRS lists it; the IRS record is the official one. Organizations only: no people are named on these pages.