Another thought... Not filing because you owe no tax works for the majority of Thais because they earn under the threshold amount (net taxable income of 150,000 baht per annum). However, the key difference between them and us is that the average Thai doesn't have overseas sources of income, bank accounts or investment income - most expats have at least one of these. Usefully - for the Thai Revenue Department, anyway - there is now the cross-border sharing of tax and financial information. I know it as the Common Reporting Standard (CRS); U.S. citizens know it as FATCA (Foreign Account Tax Compliance Act). Under this framework, countries systematically and automatically share taxpayer financial data with the authorities of the taxpayer's home country to prevent tax evasion. It's getting harder (but not impossible) to hide. I feel I've pre-emptied any Revenue Department interest in me by telling them before they might ask.