Minn. Stat. § 354A.21
A teacher who terminates employment at any time during the academic year at the end of which the teacher is required to terminate employment pursuant to this section shall be entitled upon application to a proportionate retirement annuity pursuant to section 356.32. Nothing contained in this section shall preclude a district from employing a retired teacher as a substitute teacher but upon having earned an amount equal to the annual maximum earnings allowable for that age for the continued receipt of full benefit amounts monthly under the federal old age, survivors and disability insurance program as set by the secretary of health and human services pursuant to the provisions of United States Code, title 42, section 403, in any academic year from employment as a substitute teacher, any person over the age of 70 years shall terminate employment for the remainder of that academic year. No person employed as a substitute teacher after reaching the normal retirement age and who has retired under this chapter shall resume membership in the teachers retirement fund association by virtue of the employment as a substitute teacher.
Minn. Stat. § 354A.21
1975 c 306 s 32; 1976 c 329 s 31; 1979 c 217 s 12; 1980 c 342 s 14; 1Sp1981 c 4 art 2 s 35; 1987 c 284 art 2 s 6; 1989 c 319 art 13 s 73