Minn. Stat. § 354.72
Subd. 1. Application.
This section applies to any strike period under section 354.05, subdivision 13, clause (9), and to any period of authorized leave of absence without pay under sections 354.093, 354.094, 354.095, and 354.096 for which the teacher obtains credit for allowable service by making payment as specified in this section to the Teachers Retirement Association fund. Each year of an extended leave of absence under section 354.094 is considered to be a separate leave for purposes of this section.
Subd. 2. Purchase procedure.