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
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
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
Withum Orange County in the News
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,…
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…
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…
Los Angeles Business Journal Names Two Withum Partners as Top Advisors in the San Fernando Valley
Chris Passmore and Steve Martini have made a lasting impact across the San Fernando Valley through their leadership, business advisory skills and community involvement. Recognized for helping businesses navigate change, create opportunity and drive growth, they have strengthened the region’s business community while contributing to its long-term economic vitality. Chris Passmore is the Partner-in-Charge of Withum’s…
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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