(a) A retired teacher who enters into a position in public service, other than a retired teacher who has not attained age 65 in a calendar year and is employed in a substantially full-time position of public service under which the retired teacher will earn more than the amount permitted under section 212 of the Retirement and Social Security Law during such calendar year or who is not permitted under the provisions of the Internal Revenue Code, and the rules and regulations promulgated thereunder, to receive a retirement allowance while being employed in public service, shall be entitled to elect the benefits of section 212 of the Retirement and Social Security Law. Such retired teacher shall be presumed to have elected the benefits of section 212 of the Retirement and Social Security Law. Such presumption, however, shall not apply to a retired teacher who earns or purchases retirement credit in a public employee retirement system of New York State for such service.

(b) A retired teacher who has elected the benefits of section 212 shall receive his or her retirement allowance during the portion of a calendar year in which he or she earns an amount in such calendar year which is no greater than the maximum amount permitted under section 212. However, if such retired teacher earns any amount in excess of the maximum amount in a calendar year, his or her retirement allowance shall be suspended for the period during which such excess amount is earned.

(c) A retired teacher who has not attained age 65 during a calendar year and enters into a regular position in public service under which the retired teacher will earn more than the amount permitted under section 212 of the Retirement and Social Security Law during such calendar year shall notify the system upon entering into such employment.