Taxes in Thailand
The liability to pay taxes in Thailand commences latest after a stay of 180 days in the country. You may find further information on the website of the Thai "Revenue Department" (en).
Your tax identification number (Tax ID) can be obtained from the Area Revenue Office at your place of stay. The area revenue office informs you furthermore on the income which is considered assessable in Thailand and therefore to be declared. A map with contact details of the different revenue offices can be found on the website of the Thai “Revenue Department”.
Thailand has concluded several "agreements on avoidance of double taxation". Please find the agreement with Switzerland on the website of the Swiss Government (de).
The Regional Revenue Office in Thailand is charged with issuing necessary certificates (e.g. Certificate of Tax Residence) in order to file for reimbursement of withholding tax according to existing agreements.