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
Beyond the Region
- Inside Public Accounting Top 100 Firms – 23rd 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
Withum in the News
Alan Iosue Named 2026 LA Times Entertainment Business Visionary
As a trusted advisor to entertainment clients, Alan helps organizations navigate the unique opportunities and complexities of an increasingly dynamic, deadline-driven industry. This recognition reflects his commitment to delivering strategic guidance that supports both immediate business needs and long-term success across Southern California’s creative economy. Alan advises production companies, professional athletes, arts organizations and closely…
Withum Ranked a Top 20 Firm Among 2026 IPA 100 Firms
The annual IPA 500 ranks the 500 largest accounting firms in the United States by net revenue using data submitted through the IPA Practice Management Survey. A Growth Strategy Guided by The Withum Way Withum’s rise into the Top 20 reflects purposeful investment. As an independent, owner-operated firm, Withum has the flexibility to make long-term investments that support sustainable growth while maintaining its culture and deepening client relationships. Innovation…
Robin Kim Joins Withum Capital as Managing Director of Investment Banking
Robin brings more than 20 years of investment banking and principal investing experience, advising founder-led, family-owned and privately held companies. Throughout his career, he has advised on transactions exceeding $30 billion in aggregate value, including M&A transactions, leveraged buyouts, recapitalizations, restructurings and debt and equity financings. His experience spans a broad range of industries, providing…
Chelsie Rabon Named 2026 Next Generation in Accounting Winner
Chelsie is a leader in Withum’s San Ramon, CA, office, where she specializes in audits of employee benefit plans, labor organizations and multiemployer benefit plans. She was recognized for her dedication to clients, technical proficiency and ability to help organizations address audit and compliance requirements. Chelsie is deeply committed to fostering the next generation of…
Los Angeles Business Journal Names Two Withum Partners as Top Advisors in the San Fernando Valley
Chris Passmore and Steve Martini have made a lasting impact across the San Fernando Valley through their leadership, business advisory skills and community involvement. Recognized for helping businesses navigate change, create opportunity and drive growth, they have strengthened the region’s business community while contributing to its long-term economic vitality. Chris Passmore is the Partner-in-Charge of Withum’s…
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