Technical foundation
Deep experience with US GAAP, IFRS, financial reporting, internal controls and complex business events.
About JCK
Technical excellence. Practical advice.
JCK Yoonsung LLP is an independent professional services firm providing assurance, SOX compliance, accounting advisory, tax and transaction services to U.S. and multinational organizations.
Our firm
A firm built for complex reporting, controls and business decisions.
We support organizations that need more than routine compliance. Clients engage JCK for accounting judgment, assurance discipline, SOX and internal controls support, tax planning and transaction perspective delivered by experienced professionals who remain close to the work.
Business orientation
We connect technical answers to business impact, management priorities and implementation realities.
Global readiness
We support U.S. companies and multinational organizations with cross-border reporting and advisory needs.
Our reach
U.S. execution with a global perspective.
Headquartered in Southern California, JCK serves clients across the United States and maintains an additional presence in the New York and New Jersey metropolitan area. Through our strategic alliance in Korea, we also support cross-border reporting, tax and advisory needs.
Domestic capabilities
Assurance, SOX, accounting, tax and transaction support for organizations operating across the United States.
Korea–U.S. expertise
Support for U.S. subsidiaries, multinational groups and organizations navigating cross-border reporting and compliance.
Experienced professionals
Direct access to partners with technical depth and practical business judgment.