Revenue Department data show about 5 million of roughly 12 million personal income tax filers actually owe tax, and an estimated 21-22 million of Thailand's near-40 million workers sit outside the formal tax system. Economists are split: KKP Research and TDRI say raise incomes first, while the Revenue Department and Finance Ministry want informal workers brought into the data system. The article gives no new rule or deadline, so for now it is background. Watch for any move to tighten registration or lower the roughly 150,000 baht taxable threshold, since either would hit small traders and micro-enterprises directly.