On September 15, Revenue Departmental Order No. Por. 161/2566 was published, fundamentally changing how Thailand tax residents’ offshore-sourced income will be taxed. Under the order, starting from January 1, 2024, the offshore-sourced income of tax residents will be subject to Thai personal income tax (PIT) in any year that it is brought into Thailand. The purpose of this new rule is to ensure consistent tax collection practices among tax officers and to tackle tax avoidance strategies commonly used by individual taxpayers. PIT on Offshore-Sourced Income According to the resident rule in Thailand’s Revenue Code, Thailand tax residents (i.e., persons who reside in Thailand for at least 180 days in a calendar year) are subject to PIT on their domestic-sourced and offshore-sourced income. “Offshore-sourced income” is broadly defined to include income from work, business, or assets outside Thailand. Existing Practice Currently, Thailand tax residents’ offshore-sourced income is exempted from PIT if it is brought into Thailand after the calendar year in which it was earned. This exemption was adopted 28 years ago in the Revenue Department’s interpretation stated in a resolution from February 1985. This exemption by interpretation has led some Thailand tax residents to avoid PIT by simply holding their newly earned offshore-sourced income abroad temporarily and then bringing it into Thailand at a later time. Through the years, a number of tax rulings have affirmed this practice. New PIT Collection Rules for Offshore-Sourced Income Revenue Departmental Order No. Por. 161/2566 simply revokes the favorable exemption adopted under the February 1985 resolution so that the delay tactic is no longer able to succeed in avoiding tax. Starting from January 1, 2024, the offshore-sourced income of Thailand tax residents will be subject to PIT whenever it is brought into Thailand, at which time the offshore-sourced income must be declared to