You can become a snowboard instructor at 16, depending on the route you take. A 16 year old can take the CASI and SBINZ level 1 and 2 exams and can teach once certified so long as you have a work permit, or citizenship for the country where you want to teach.
Snowboarders can take the BASI level 1 and 2 exams at 16 years old, however the licence won’t be valid until age 18 (you won’t need to retake the exams). Once age 18 you can work as an instructor with a BASI certification.
There is no such thing as being ‘too old to become a snowboard instructor’, in fact, becoming a snowboard instructor as part of a career break or retirement is a popular option. At Winter Sports Company we have had participants as young as 16 and up to age 76 join us in resort!
Many resorts like their instructors to be age 18+ to work, however we have known 16 year olds to be gain employment on a part time basis in Canada. There is no upper age limit to work as an instructor, providing you have the right to work in the country where you want work.