The core document set, in plain terms
Nearly every teach-abroad application, regardless of country, eventually asks for some combination of: a valid passport (often with 6+ months validity remaining), an accredited TEFL certificate, a degree certificate and transcript (where the country requires a degree), and a criminal background check from your home country. Beyond that, requirements branch depending on where you're headed.
Some countries add a health certificate or medical check, particularly ones with stricter work-visa medical screening. Others want passport-style photos in a specific format, a signed CV, or reference letters from previous employers or professors.
