In Thailand, you file your annual personal income tax return, Form PND 91, yourself.
The deadline is 31 March of the year after the tax year — income earned in 2025 is filed by 31 March 2026. If you file online through the Revenue Department, you get a short extension of about a week; the Revenue Department sets the exact online deadline each year.
You file directly with the Thai Revenue Department, either at a district Revenue office or online at its website. PND 91 is the return for people whose income comes from employment only.
