Basic Concept
The Personal Income Tax is a direct tax collected from income earned from sources within or outside Thailand during the taxable year.
An individual residing in Thailand for one or more periods aggregating 180 days or more in any tax year (calendar year) is deemed to be a resident of Thailand.
Income derived abroad by a resident of Thailand is subject to tax only when the income is brought into Thailand.
A non-resident however is subject to tax only on income derived from sources within Thailand.