(a) The retirement allowance of a disability beneficiary shall be reduced in the event that any such disability beneficiary is employed in an occupation paying more than the difference between his retirement allowance, as it would be without optional modification, and the final salary. The retirement allowance shall be adjusted to a sum which, when added to the amount so earnable, shall equal the final salary. If the earnings subsequently change, the retirement allowance shall be adjusted so that the sum of retirement allowance when added to the amounts earned shall not exceed his final salary. The reduction shall be from the amount that the allowance would have been without optional modification. The retirement allowance of a disability beneficiary shall not be reduced after he or she has attained the applicable mandatory retirement age, or shall have attained the age and the date such beneficiary would have been eligible for service retirement under applicable law had he or she remained in continuous service from the date of retirement. For the purposes of this section, applicable law shall mean the plan and/or provision under which the member was enrolled on the date the disability retirement became effective.

(b) In the event that a disability beneficiary is restored to active service of an employer, at a salary equal to or in excess of his final salary, his retirement allowance shall cease. Thereafter, such person shall contribute to the retirement system in the same manner and at the same rate that he paid prior to his disability retirement. The total service which was credited at the time of such retirement shall be credited to the restored individual. Upon subsequent retirement, additional service earned by him subsequent to his last restoration to membership will be credited.

(c) In the event that a disability beneficiary is restored to active public service at a salary less than his final salary but equal to or in excess of the current minimum salary for the position from which he was last retired for disability, such person, if he or she so elects, shall again become a member of the retirement system and the retirement allowance shall cease. If such an election is filed with the Comptroller, such individual shall contribute to the retirement system in the same manner and at the same rate as was paid prior to disability retirement. The total service which was credited at the time of such retirement shall be credited to the restored individual. Upon his subsequent retirement, additional service earned subsequent to the last restoration to membership will be credited.