What documents are required for a 30-day tourist visa extension in Thailand?

To extend a 30-day tourist visa in Thailand, the essential documents generally required are your passport, 1900 baht fee, and a filled-out application form. However, requirements can vary by immigration office. Some offices may also ask for passport copies (including the bio page, visa, and entry stamp), a passport-sized photo, and potentially a TM30 form depending on your circumstances. It's best to check the specific requirements of the immigration office you plan to visit.