Q. Does you taking online courses/classes for teacher certifications count as school, for the education/tuition credits?
A. Probably not. Schools that only offer online courses usually do not qualify. Online classes taken at schools that also have classroom instruction usually do count. If the school does not issue you a form 1098-T, for the tuition you paid, it is most likely not an "eligible institution".
Q. I have successfully completed the courses and paid for them. Does this count as full time student?
A. No. "Full time" is defined by the school and usually is set number of hours. But you do not need to be full time to claim an education credit.
See: https://www.eitc.irs.gov/other-refundable-credits-toolkit/compare-education-credits/compare-educatio...
Continuing Education. Regular W-2 employees are no longer (since 2018) allowed to deduct job expenses, including education. If you're self employed, you can deduct the cost, as a business expense, on schedule C.
If the courses were taken at a recognized college or vocational school (educational institutions eligible to participate in the student aid programs administered by the Department of Education), you can, instead, take either the Lifetime Learning Credit or (less likely) the American Opportunity credit.
