Tax Services
Orange County, CA
Located in the heart of Irvine’s business district, Withum is one of the nation’s top-rated and largest accounting firms in Orange County.
Withum helps local corporations and nonprofits thrive, offering advisory, tax, audit, assurance and consulting services to the Orange County business community. We are more than just an Irvine accounting firm, we are a strong national resource providing all the traditional CPA and accounting services businesses and individuals require, plus a whole suite of advisory solutions to accelerate your success. That’s the Power in the Plus!
(949) 261 2808
Orange County Service Specializations
Assurance and Accounting
Employee Benefit Plan Audits
Outsourced Accounting Systems and Services
Public Company SEC Compliance & Reporting
Transaction Advisory
CA State and Local Tax Updates
Do you or your organization operate in multiple states? Do you own property in a variety of states? California 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 California 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 Orange County
Withum in the Orange County Community
While our primary focus is serving the business needs of Orange County, we’re enthusiastically committed to giving back to the people and organizations that support local development. Whether it’s through our annual holiday drive, where we’ve collected thousands of essential items for local charities, or through active involvement on nonprofit boards, growth networks and hands-on volunteer work with organizations like Olive Crest and Second Harvest OC, our team is proud to step outside the office and into the heart of our community.
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
Kenneth L. Johnson, CPAKen is the Partner-in-Charge (PIC) of the firm’s Orange County office. Ken brings nearly three decades of expertise in conducting audits and reviews for both privately held and publicly traded companies.
In addition to his successful career working with and advising the firm’s clients, Ken dedicates much of his time to non-client-focused activities, such as the daily operations and people strategy of the Orange County office and its growth in the local marketplace. He is passionate about mentoring the next generation and providing them with the same opportunities he had. Ken is helping the younger team members grow the firm and contribute to this office’s legacy of entrepreneurship. By acting as a business owner first, he is setting an example to the office of the advisory experience we should bring to our clients, above and beyond the compliance work of audits and tax.
Orange County Leadership
Industry Leader, Partner
Orange County, CA
Partner
Orange County, CA
Partner
Orange County, CA
Partner
Orange County, CA
Partner
Orange County, CA
Partner
Orange County, CA
Partner
Orange County, CA
Withum in the News
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. “Withum’s new website is built for…
Kelsey Thomas Named Opus Connect’s 2025 Woman of the Year
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 we value within our community. She has been instrumental in facilitating our Women in M&A programming and…
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….
BINJE Names Marcus Dyer to 2026 Best Black Business Leaders List
Marcus draws on his law background to represent clients in commercial and tax disputes before state courts, Federal District Court and the United States Tax Court, frequently resolving matters through alternative dispute resolution rather than litigation. As an industry thought leader, Marcus contributes to a wide range of publications, helping businesses and individuals navigate high-risk…
Withum Celebrated New Orange County Office With An Open House
The space, which officially opened in December 2025, offered guests sweeping panoramic views of the region as they toured the thoughtfully designed team collaborative spaces, modern amenities and community spaces that echo Withum’s culture and values. The striking backdrops of the Irvine business hub, Orange County canyons, San Joaquin Hills, Saddleback and San Bernardino Mountains…
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