AO Accounting & Advisory Ltd., formerly known as Administration Outsourcing Co., Ltd. (AO), was established in 2006 and has since expanded to serve over 100 organizations annually, both in Thailand and internationally. In 2024, the company rebranded as AO to reflect its strategic growth, enhancing its service portfolio to include comprehensive legal and advisory solutions.  

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In January 2025, AO further solidified its market position by merging with Asia Accounts and Services Co., Ltd., a highly regarded firm recognized among the Top 5 Xero Advisors in Thailand. In 2023, Asia Accounts was honored with the “Outstanding Small Company” award at the Thailand International Business Awards, hosted by the British Chamber of Commerce Thailand. Following the merger, the company now operates as AO Accounting & Advisory Ltd., with a team of 45 experienced professionals offering a full spectrum of services, including accounting, legal, compliance, and business advisory solutions.  This transformation reinforces AO’s commitment to delivering comprehensive, high-quality support to its diverse and expanding client base, ensuring its continued leadership in the industry.