Only 5 million of 12 million Thai income tax filers actually pay tax, with an estimated 21–22 million workers entirely outside the formal tax system. The core issue is not evasion but subsistence-level incomes (below 150,000 baht/year threshold) and weak perceived returns on tax paid. Thai policymakers debate sequencing: whether to raise incomes first (to organically expand the tax base) or formalize the 21 million workers now. Nordic comparisons show high compliance rates correlate with high wage floors and visible social returns, not just high tax rates.