(a) The membership of the retirement system shall consist of the following: All persons who shall become teachers after the date of establishment shall become members of the retirement system as a condition of their employment. Any person who is a teacher on the date of establishment shall become a member as of that date unless within a period of 90 days next following such teacher shall file with the Board of Control on a form prescribed by the board a notice of his election not to be covered in the membership of the system and a duly executed waiver of all present and prospective benefits which would otherwise inure to him on account of his participation in the retirement system.

(b) A teacher in service on October 1, 1973, whose membership in the retirement system was contingent on his own election and who elected not to become a member may thereafter apply for and be admitted to membership with all prior service credit and with all membership service credit as otherwise provided for in this chapter by applying for such membership within 150 days from September 17, 1973; provided, that said teacher pays to the treasurer of the said retirement system on or before October 1, 1974, a sum equal to the total contributions which he would have made as a member during the period of his employment as a teacher from September 1, 1941, to the date of his application for membership, plus compound interest of eight percent on such contributions. Any member or any retired member who at one time taught as a nonmember may now receive credit for prior service and for the years taught as a nonmember; provided, that member or retired member, within 150 days from September 17, 1973, pays to the treasurer of the said retirement system a sum equal to the total contributions which he would have made as a member during the period of his employment as a teacher from September 1, 1941, to the date he or she became a member, plus compound interest of eight percent on such contributions. As soon as practicable after the expiration of the time for making such elections, the Department of Education, at the request of the Governor, shall furnish him or her a report of the number of teachers in service who applied for membership or credit for prior service. The Board of Control of the Teachers' Retirement System shall determine and report to the Governor the employer cost for such coverage.

(c) The Board of Control may, in its discretion, deny the right to become members to any class of teachers whose compensation is only partly paid by the state or who are serving on a temporary or other than per annum basis, and it also may, in its discretion, make optional with members in any such class their individual entrance into the retirement system. Should any member in any period of six consecutive years after becoming a member be absent from service more than five years or withdraw his or her contributions, as provided in subsection (g) of Section 16-25-14, or retire or die, he or she shall thereupon cease to be a member.

(d) Notwithstanding, a teacher in service on October 1, 1975, who has full-time military service in the armed forces of the United States, exclusive of service in a reserve or national guard component of any branch of the armed forces, and who has not received credit toward retirement status in the Teachers' Retirement System of Alabama for said military service, may be granted by the Board of Control membership service credit for the period of such service in the armed forces; provided, that such member pays into the Teachers' Retirement System, in a lump sum prior to October 1, 1976, an amount equal to four percent of the average compensation paid to a teacher during each claimed year of full-time military service, plus and together therewith, eight percent interest compounded from the last date of such claimed military service; provided further, that such a member shall not receive membership service credit for more than four years of military service and shall receive no credit for military service if such member is receiving military service retirement benefits, other than disability allowances or benefits, from any branch of the United States armed forces or by reason of any such service in any branch of the armed forces or if such member received anything other than an honorable discharge for and including the claimed military service.

(e) Anything in this chapter to the contrary notwithstanding, if any person becoming a member of the Teachers' Retirement System after October 1, 1975 shall have served in the armed forces of the United States, exclusive of service in a reserve or national guard component of any branch of the armed forces, such member may be granted by the Board of Control membership service credit for such period of service in the armed forces; provided, that such member pays into the Teachers' Retirement System, in a lump sum within one year next after the first day of the pay period in which the first deduction to the Teachers' Retirement System is made, after having been honorably discharged from the armed forces, an amount equal to four percent of the average compensation paid to a teacher during each claimed year of full-time military service, plus and together therewith, eight percent interest compounded from the last date of such claimed military service; provided further, that no member shall receive more than four years' membership service credit for military service, and no credit for military service shall be granted if such member is receiving military service retirement benefits, other than disability allowances or benefits, from any branch of the United States armed forces or by reason of any service in any branch of the armed forces or if such member received anything other than an honorable discharge for and including the claimed military service.

(f) Anything in this title to the contrary notwithstanding, any member who, at the time of his or her withdrawal from service, has completed the age and service requirements established by the Board of Control for eligibility for deferred benefits shall be eligible to continue in the membership of the system until he or she files application for service retirement in accordance with the provisions of Section 16-25-14. The Board of Control shall, from time to time, establish the minimum age and the minimum number of years of creditable service which shall be required in order that a member may be eligible for deferred benefits; provided, that such minimum number of years of creditable service shall not be less than 10 years nor more than 25 years.