TESOL certification does not expire; once you receive your certificate, it lasts a lifetime. Some teachers continue building on their initial certification in order to qualify for more jobs by upgrading their course to add more hours of training or by earning a specialized TEFL/TESOL certificate in a high-demand teaching area, such as teaching English online or teaching young learners or a shorter TEFL micro-credential course in a current ESL topic.
Hawra Saleh, Bridge grad, with her TEFL/TESOL certificate

Hawra with her Bridge TEFL/TESOL certificate

TEFL and TESOL are common acronyms in the world of English language teaching and they are used interchangeably by most TEFL providers and language schools. Despite this common usage, it’s helpful for anyone entering the field of teaching English to speakers of other languages to have a clear understanding of what TESOL is, and the nuances between these two terms.