In the case where an optional benefit has been selected, such reduction shall be the same as the reduction would have been without optional modification. Where such reduction is greater than the pension, including the pension-providing-for-increased-take-home-pay, payable under the option selected, the excess may be paid by the pensioner into the funds of the system, in which case the benefit due under the option shall be paid as if no reduction had occurred. If such excess is not paid by the pensioner, the benefit otherwise due under the option shall be reduced by the actuarial equivalent of such excess. In no event shall the payment to the funds be greater than the difference between the pension, including the pension-providing-for-increased-take-home-pay, without optional modification and the pension, including the pension-providing-for-increased-take-home-pay, under the option selected. The pension, including the pension-providing-for-increased-take-home-pay of a disability pensioner, shall not be reduced after he has attained the mandatory retirement age applicable to him or shall have attained the age or performed the period of service specified by applicable law for eligibility for a service retirement benefit.
N.Y. Retire. and Soc. Sec. Law § 102