Once you become tax resident any assessable income that you remit into Thailand may be subject to taxation. Whether you actually pay any tax is dependent on your own personal financial circumstances.
To get a Thai tax residency certificate from your local Revenue Office you need the following:
1. A copy of the filed income tax returns e.g. P.N.D. 90, P.N.D. 91.
2. A copy of tax receipt.
3. A copy of taxpayer's tax identification card.
4. A copy of taxpayer's passport (in order to total number of days the taxpayer resides in Thailand. In order to issue the certificate, the taxpayer must resides in Thailand more than 180 days).