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
Fortune Media and Great Place To Work Name Withum to 2026 Best Workplaces in Consulting & Professional Services
Withum ranks number 23 in the large company category. Earning a spot on the list means that the Firm is one of the best companies to work for in the country. The Best Workplaces in Consulting & Professional Services award is based on an analysis of survey responses from over 125,000 employees at Great Place…
NJBIZ Names Sara Palovick a 2026 Leading Woman in Business
As a tax partner, Sara serves clients across the real estate industry, specializing in partnership and individual taxation. She advises closely held and institutional real estate businesses on tax compliance, strategic planning and succession, helping clients navigate tax matters while supporting long-term growth and continuity. Sara is a recognized thought leader on real estate taxation,…
Withum Capital Advises World Flavors on Sale to Main Street Capital Holdings
Withum Capital advised the shareholders of World Flavors throughout the transaction process, helping evaluate strategic alternatives and identify a capital provider aligned with the shareholders’ objectives, culture and long-term vision for the business. The transaction marks a significant milestone for World Flavors, a multi-generational family-owned business with more than 50 years of operating history. The…
Buffalo Business First Names Michelle Sullivan to 2026 Power 200 Women List
Leadership in Audit and Advisory As an audit partner with more than 30 years of experience, Michelle serves clients in the not-for-profit, employee benefit plan and real estate sectors. Her nonprofit expertise spans health and welfare organizations, higher education and cultural institutions and public foundations with significant investment and endowment assets. Michelle works closely with…
LA Times Names Two Withum Partners as Private Equity and M&A Visionaries
Johnny Minassian Johnny Minassian is a partner providing assurance, accounting and consulting services to investment advisers and private funds. He serves hedge, commodity, private equity, venture capital, loan and real estate funds throughout their life cycles. Johnny has helped grow the Firm’s Financial Services practice in Southern California and is connected to the deal community,…
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