What is a Thai tax ID number?

A Thai tax ID is a 13-digit number the Revenue Department uses to identify every taxpayer. For individuals, a Revenue Department notice effective February 1, 2012 made the national ID card number (under the civil registration law) serve directly as the tax ID, so no separate application is needed. For juristic entities such as companies and partnerships, the 13-digit juristic registration number issued by the Department of Business Development (DBD) at incorporation becomes the entity's tax ID immediately, with no extra step at the Revenue Department. Checking a tax ID depends on what you need to verify. To confirm whether a supplier or business partner is VAT-registered, use the Revenue Department's VAT INFO system at vsinter.rd.go.th: enter the 13-digit tax ID and it returns the business name, address, and operating status (note this is a different system from VRT, which only verifies retailers approved to refund VAT to tourists). To confirm a company's registration and current status, use DBD DataWarehouse+ at datawarehouse.dbd.go.th, searching by company name or the 13-digit juristic number. Both tools are free; reconfirm details at rd.go.th and dbd.go.th before relying on them for anything legal. For online sellers opening a shop on Shopee, Lazada, TikTok Shop, or LINE MyShop, no new tax ID is needed since the existing citizen ID already applies. The number matters more once you issue tax invoices to corporate buyers, or once revenue passes 1.8 million baht a year and you register for VAT and receive a PP20 certificate. Several marketplace platforms also request a seller's tax ID during shop verification, so they can issue withholding tax documents correctly.