Those who already hold a visa that allows for one-year extensions (by reasons of marriage, investment, or Elite visa) are able to manage their Thai-American Amity treaty companies without a work permit.
Those who do not require a work permit will still be required to pay personal income tax; if a corporation then you are paid a salary and you pay personal income tax on that. If you have a Sole Proprietorship, then you pay a percentage of your income if you use the standard fixed deduction. If you use expenses with receipts, then it’s the personal income tax on your net profit.
Foreign Business License
US Treaty Of Amity
Thailand Work Permit
Closing a Thai Company