Tax Services
Portland, OR
Located in South Portland, Withum is a leading Portland CPA firm focused on accounting, tax and advisory services.
As a top 25 national firm, Withum’s dedicated team members serve organizations across industries that range from startups to global enterprises. We are a technology-driven firm helping the Portland community grow and thrive with services ranging from cybersecurity and forensics accounting to employee benefit plan audits and outsourced accounting services…plus a whole suite of advisory solutions that will level up your success. That’s the Power in the Plus!
(818) 789 1179
Portland Service Specializations
Assurance and Accounting
Cybersecurity
Forensic and Valuation Services
State and Local Tax
Outsourced Accounting Systems and Services (OASyS)
Oregon State and Local Tax Updates
Do you or your organization operate in multiple states? Do you own property in a variety of states? Oregon 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 Oregon 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 Portland
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.
Portland Leadership
Withum in the News
Withum Announces 2026 Firmwide Leadership Transitions
This next generation of leaders step forward at a pivotal time for the Firm, bringing the technical expertise and strategic perspective needed to navigate continued growth, rapidly advancing technology and an ever-evolving industry landscape. Grounded in the Withum Way mentality, they will shape what’s ahead while preserving the culture that remains central to how the…
Withum Names Eighteen New Partners
Introducing Our 18 New Partners
Withum’s Columbia Office Welcomes Greater Baltimore
Withum team members, clients and community leaders, including representatives from Howard County and the Central Maryland Chamber, came together to mark the official “door opening” on the new location. The ribbon-cutting ceremony highlighted the evening, which featured citations presented by community leaders welcoming Withum to the Columbia region and recognizing its strong ties to the…
Nadia Matthie Appointed as Chair of the AICPA’s Employee Benefit Plans Expert Panel
The AICPA’s Employee Benefit Plans Expert Panel was formed to protect the public interest and agree on key plan issues by leveraging the knowledge of leaders in the employee benefit plan industry. Nadia’s deep expertise makes her a valuable asset to help further the panel’s mission as Chair of the group. Nadia has more than…
Chris Passmore Named Top Leader on Los Angeles Business Journal List for Fourth Consecutive Year
As partner-in-charge of Withum’s Los Angeles office, Chris plays a pivotal role in the Firm’s growth on the West Coast. With nearly 25 years of experience in the profession, he specializes in assurance and business consulting services to emerging and middle-market companies. In addition to serving technology companies and professional services firms, Chris holds an advanced-level certificate in 401(k)…
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