You need to be 16 to take the CSIA and NZSIA level 1 and 2 exams and can teach once qualified so long as you have the right to work in the country where you want to teach.
Individuals can take the BASI level 1 and 2 exams at age 16+, however your licence won’t be valid until age 18. Once age 18 you can work as an instructor with a BASI certification.
There is no upper age limit to become an instructor, in fact, it is a very popular option to take a ski instructor course as part of a career break or during retirement. At Winter Sports Company we have had participants as young as 16 and up to age 76 join us in resort!
Most resorts require instructors to be age 18+ to work, however we have known 16 year olds to be employed on a part time basis in Canada. There is no upper age limit to work as an instructor – so long as you have the right to work in the country where you wish to be employed.