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
LA Times Names Two Withum Leaders on its Banking and Finance Visionaries List
About Aza Ghazaryan Aza Ghazaryan is a Tax Partner with over 20 years of experience serving as a trusted advisor to partnerships and high-net-worth individuals on tax planning and compliance. She advises clients across industries, including professional services, real estate, technology and not-for-profit. Aza has successfully guided clients and teams through complex regulatory changes, including the Tax Cuts and Jobs Act, federal…
Withum Launches Unified Client Collaboration Platform to Simplify Client Engagement Across the Service Lifecycle
ClientConnect consolidates traditionally disconnected client-facing tools into a single platform, reducing complexity across the engagement lifecycle—from request intake and document exchange to deliverables and payment. The solution reflects Withum’s continued investment in digital transformation while addressing the evolving expectations of today’s clients. ClientConnect features a modular architecture supported by native integrations and open APIs. Core components include request management, e-signatures,…
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
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 expertise and impactful leadership within the deal space. She has championed initiatives spanning business development, client service and value-driven insights. “Kelsey represents the standard…
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….
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