There are many different levels of TEFL qualification, just as with other certification. Once you have the basic TEFL qualification, you could opt to progress further and study for a Diploma or a Master's degree in TEFL. Most of these qualifications require experience in teaching (usually two years of full-time).
Some options include:
Providing they meet the criteria for input, observed teaching practice and external validation, the following are also acceptable:
These qualifications will enable you to apply for more senior positions, both in teaching and in academic management.
There are other courses that specialise in certain areas of TEFL, for example, teaching Young Learners and Business English.
These courses will enable you to specialise and may give you the edge when applying for positions within your chosen field.