Tax Services
Seattle, WA
Located in North Seattle, Withum is a leading Seattle CPA firm with a robust ERISA practice, enhanced forensic capabilities and the ability to offer outsourced accounting and cybersecurity services locally and nationwide.
Ranked in the top 25 firms in the nation, Withum’s team of passionate professionals offer advisory, tax, audit and assurance services to the Seattle business community…plus a whole suite of advisory solutions that will level up your success. That’s the Power in the Plus!
(206) 522 6370
Seattle Service Specializations
Assurance and Accounting
Forensic and Valuation Services
Cybersecurity
Outsourced Accounting Systems and Services (OASyS)
Washington State and Local Tax Updates
Do you or your organization operate in multiple states? Do you own property in a variety of states? Washington State and Local Tax (SALT) laws are always changing and understanding the nuances of the states that you own or operate in is challenging. In these Washington resources, you’ll find just a dash of the most up-to-date details on rules and regulations as state and local tax changes happen by state!
Industries We Focus on in Washington
Withum in the Seattle Community
Community is a core pillar of the Withum Way, and our team thrives in the office and supporting the Greater Seattle area. We partner with local organizations through community service, events and more. The team focuses on supporting organizations that empower the community locally and throughout Washington state, strengthening the neighborhoods in which we live and work.
Beyond the Region
- Inside Public Accounting Top 100 Firms – 22nd Largest Nationally
- Accounting Today Top 100 Firms – 22nd Largest Nationally
- Great Place to Work® – Fortune Best Workplaces for Parents and Women
- Vault Top 25 Accounting Firm
Partner In Charge
Joseph M. Thiermann, CPAJoe is a partner with over 25 years of specialized audit experience with audits of defined contribution plans, defined benefit plans, health and welfare plans, labor organizations and not-for-profits. He conducts system-wide reviews, designs and implements accounting systems and works on special projects involving system design, expense reporting and compliance, often in conjunction with other professionals to resolve regulatory and general management issues for clients.
Joe is an avid public speaker, having presented at the Annual Conference of the International Foundation of Employee Benefit Plans (IFEBP), the IFEBP Accountants’ Institute and the Oregon Labor Law Conference, and even taught business courses to contractors.
Seattle Leadership
Partner
Seattle, WA
Partner
Portland, OR
Withum in the News
Withum Launches Redesigned Website to Support AI-Driven Search and Intuitive User Experience
The new site emphasizes clarity, speed, and accessibility—making it easier for users to find relevant content, explore the Firm’s services, and connect directly with Withum’s people and expertise. The Firm’s newly redesigned website reflects a shift in delivering insights digitally by aligning user experience, modern search behavior and growth strategy under a single, purpose-built platform. More than a visual refresh, the…
Kelsey Thomas Named Opus Connect’s 2025 Woman of the Year
This annual recognition honors a member who demonstrates exceptional commitment to the Opus Connect community through consistent participation, leadership and meaningful support of peers. Kelsey was recognized for her commitment to advancing the industry and its community through an M&A lens. Throughout her over 15-year career in public accounting, Kelsey has distinguished herself through seasoned…
Linda Howard Named to Women in CX’s Awesome Women to Follow in CX List
Linda is an active member of Women in Client Experience, Women of Withum and the Association for Accounting Marketing’s Client Experience Circle. She believes in building networks and sharing best practices to strengthen client and team member service experiences. “Linda has been a driving force in shaping what a client experience program will look like at Withum….
BINJE Names Marcus Dyer to 2026 Best Black Business Leaders List
Marcus draws on his law background to represent clients in commercial and tax disputes before state courts, Federal District Court and the United States Tax Court, frequently resolving matters through alternative dispute resolution rather than litigation. As an industry thought leader, Marcus contributes to a wide range of publications, helping businesses and individuals navigate high-risk…
Withum Celebrated New Orange County Office With An Open House
The space, which officially opened in December 2025, offered guests sweeping panoramic views of the region as they toured the thoughtfully designed team collaborative spaces, modern amenities and community spaces that echo Withum’s culture and values. The striking backdrops of the Irvine business hub, Orange County canyons, San Joaquin Hills, Saddleback and San Bernardino Mountains…
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