What is the most popular and easiest business structure to set up?
The most popular Thai legal entity would be the Thai Limited Company, or a Private Thai Limited Company, to be exact. Thailand has a lot of foreign investment restrictions. The Private Thai Limited Company is flexible because it allows for 51% Thai ownership, while still allowing the foreign investors to manage and control the company. According to Section 1096 of the Thai Civil and Commercial Code, a limited company requires minimum of 3 shareholders (promoters) and shares are privately owned. The personal liability of the shareholders are limited to the amount unpaid on their shares. As mentioned, the Thai limited company also allows separation between the owners and management.
If 51% of the company is foreign-owned- it would be restricted by Foreign Business Act and would require 3 million baht capitalization (authorized capital requirement) for each restricted business activity. And in order to sponsor one Work Permit for a foreign employee - it requires at least 2 million baht capitalization to be fully paid-up.