Thai personal income tax: rates, TIN, and the PND90/91 filing routine

Thai personal income tax is progressive on net income after deductions and allowances: the first 150,000 baht is exempt, then 5% to 300,000, 10% to 500,000, 15% to 750,000, 20% to 1,000,000, 25% to 2,000,000, 30% to 5,000,000 and 35% above that (the 35% band was raised from 4 to 5 million baht for the 2017 tax year by Revenue Code Amendment Act No. 44). The tax year is the calendar year and the annual return is due by the last day of March of the following year — PND91 if you have only employment income, PND90 otherwise. People with rental, professional or business income also file a half-year return (PND94) by 30 September. Tax withheld at source during the year is credited against the final bill, and spouses may file jointly or separately.

The main current allowances: employment income carries a standard expense deduction of 50% capped at 100,000 baht, plus a personal allowance of 60,000 baht, 60,000 for a spouse and 30,000 per child (doubled to 60,000 for the second and each subsequent child born in or after 2018). Be warned that the Revenue Department's own English summary pages still display the pre-2017 figures (a 30,000 personal allowance and a 35% band starting at 4 rather than 5 million baht) — a common source of confusion.

A taxpayer identification number is required under Section 3 Undecim of the Revenue Code, applied for within 60 days of first deriving assessable income. Thais simply use their 13-digit national ID; foreigners apply at an area revenue office with their passport and receive a 13-digit TIN. (TINs have been 13-digit since 2012 — the Revenue Department's English TIN page still describes the old 10-digit format.)