The creditable service established under this Section may be used for all purposes under this Article and the Retirement Systems Reciprocal Act, except for the computation of the highest average annual salary under Section 12-133 or the determination of salary under this or any other Article of this Code.
If a person who retires under this Section dies before all payments of employee contribution have been made, the remaining payments shall be deducted from any survivor or death benefits payable to the person's surviving spouse or beneficiary.
All employee contributions paid under this Section shall be deemed employee contributions for the purposes of determining the tax levy under Section 12-149. Employee contributions made under this Section may be refunded under the same terms and conditions as other employee contributions under this Article.
If a person who has retired under this Section receives a retroactive increase in salary, the person's retirement annuity shall be recalculated to reflect the retroactive salary increase, and the resulting increase in retirement annuity, if any, shall be applied retroactively to the date the retirement annuity began. If the retroactive salary increase affects the monthly salary rate that was in effect for the person on the date of withdrawal, the employee contribution required under subsection (c), if any, shall also be recalculated.
The amount due the annuitant as a result of a retroactive increase in retirement annuity under this subsection shall first be applied against any part of the employee contribution required under this Section that remains unpaid; the remainder shall be paid to the annuitant in a lump sum, without interest.
40 ILCS 5/12-133.4