Documents checklist to apply for an ESLT job in Vietnam:
Higher Education Diploma: Degree no lower than a bachelor's; a specialist degree is also acceptable.
TEFL/TESOL Certificate: If your diploma is not in "English Language Teaching". Minimum of 120 hours of training.
C1 English Level Certificate: For non-native speakers (if your passport is not from the USA, Canada, UK, Australia, or New Zealand).
Document Preparation: Diplomas and certificates must be:
Notarized
Translated into English
Translations also notarized
Additionally: They really like documents here, so any additional references, certificates, diplomas, awards, recommendations are welcome. But don't spend too much effort on them if they are not readily available – no need to stress.