There are many different levels of TEFL qualification, just as with other certification. Once you have the basic TEFL qualification, you can usually progress to study for a Diploma or a Master's degree, some of which meet the requirements set by the British Council as a TEFL qualifying qualification. Most of these qualifications usually 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 in EFL, for example, teaching Young Learners and Business English.
Click here to find out what courses Cambridge RSA offers, and here to find out what Trinity College offers
These courses will enable you to specialise and may give you the edge when applying for positions within your chosen field.