according to section 76 bis, a foreign company (i.e. a company registered outside thailand) which has an employee, representative or go-between in thailand (i.e. an agent in thailand) for carrying on its business in thailand and thereby derives income or gains in thailand is deemed to be carrying on business in thailand. therefore, the salesperson in bangkok or the agent is required to file a tax return and pay thai corporate income tax on behalf of your company to the thai revenue department. in order for salesperson to be considered not an agent, it must be evidently clear that the agent is an independent agent i.e. independent from your company. perhaps guidance can be seek from board of taxation. on what may be considered an independent agent. an independent agent is one who: a) in the usual course of business, acts as an agent for foreign companies in general. not specifically or mainly for your company.
b) no contract or agreement exist between the agent and your company restricting his, hers or its right to act for other foreign companies.