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 – 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.
Portland Leadership
Withum in the News
NJBIZ Names Two Withum Leaders to Finance Power List
Pat Walsh Pat was recognized for his relentless dedication to elevating Withum’s position as a top 20 advisory, accounting and tax firm. This recognition reflects Pat’s leadership and the Firm’s consistent year-over-year growth and strategic expansions into new markets under his guidance. His commitment and contributions to the profession have earned him numerous accolades, including…
Los Angeles Business Journal Names Two Withum Leaders as Women of Influence in Accounting
Kimberly Ravenell, tax partner, was recognized for her commitment to client service and mentorship. With more than 30 years of experience advising high-net-worth individuals and closely held businesses, she provides tax planning and compliance guidance. Kim has played a key role in guiding her team and clients through significant industry and regulatory changes while supporting…
Sameer Uddin Named to Caseware’s 2026 30 Under 30
Advancing Audit Innovation Sameer has played a key role in advancing Withum’s use of audit technology, helping teams adopt new methodologies, improve efficiency and enhance consistency across engagements. A trusted resource for technology implementation, he has been instrumental in the Firm’s adoption of Caseware Cloud and Dynamic Assurance Solutions (DAS) applications. Driving Firmwide DAS Adoption…
Withum Team Members Named as INNOVATE100 Honorees
Leading Industry with a Tech–Forward Vision Matt Walsh, partner and practice leader of Withum’s Industrial and Consumer Products Services Team, was honored in the Finance/Accounting category for helping modernize the Firm’s technology ecosystem. His leadership has supported initiatives that enhance efficiency, streamline workflows and better align technology with evolving client needs, including work with Caseware…
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…
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