There is no reason why non-native English speakers should not be able to take and successfully complete a TESOL certification course. Due to the subject matter, you will require a high standard of English to work through the training, but not being a native speaker should not stand in the way of you embarking on a new career as an ESL teacher.
Are there any advantages to being a non-native English language teacher?
As a non-native English speaker you might find there are actually some advantages when teaching English abroad. The simple fact that you have already had to go through the same learning process as your students is certainly a real bonus as this can create a good rapport among the class. Often students are less afraid of making mistakes in front of a non-native English teacher and they can feel a greater incentive when taught by someone who was once at the same language level as themselves. It is also common for non-native speakers to have a better understanding of English grammar than native speakers as they have had to learn it all from scratch rather than by natural absorption.
Where do non-native English language teachers teach?
Many non-native English speakers complete a TESOL course with the intention of teaching in their home country, which has plenty of advantages for both the teacher and the students in their class. In this scenario the teacher will not need to compete with native English speakers when applying for jobs and they will share the same culture and native language as their students which can be a real benefit when building rapport in the classroom. In contrast, many others choose to head overseas where many opportunities await all nationalities. In areas where demand for teachers is particularly high, job applicants are more likely to be judged on their personalities and teaching skills rather than their native language.