Before any hazmat employee performs any function subject to the Hazardous Materials Regulations they must be trained. Recurrent training is required once every three years.
However, if a new regulation is adopted or an existing regulation is changed, that relates to a function performed by a hazmat employee, that employee must be trained on the new/revised requirements. This training must be completed before the employee performs the function and before the three year recurrent training is required. The employee only needs to be instructed on the new/revised requirements.