(a) Mandatory contributions.--A participant who did not make the election under section 5306.5 (relating to election by active members to become a Class A-5 member, Class A-6 member or plan participant) shall make mandatory pickup participant contributions through payroll deductions to the participant's individual investment account equal to 3.25% of compensation for current State service credited as a Class A-5 member or 3.5% of compensation for current State service credited as a Class A-6 member and 7.5% of compensation for current service performed solely as a participant. A participant who made the election under section 5306.5 shall make mandatory pickup participant contributions as provided under section 5306.5. The employer shall cause those contributions for current service to be made and deducted from each payroll or on such schedule as established by the board.

(b) Voluntary contributions.--A participant may make voluntary contributions through payroll deductions, through direct trustee-to-trustee transfers, or through transfers of money received in an eligible rollover into the trust to the extent allowed by IRC § 402. The rollovers shall be made in a form and manner as determined by the board, shall be credited to the participant's individual investment account and shall be separately accounted for by the board.

(c) Prohibited contributions.--No contributions may be allowed that would cause a violation of the limitations related to contributions applicable to governmental plans contained in IRC § 415 or in other provisions of law. In the event that any disallowed contributions are made, any participant contributions in excess of the limitations and investment earnings on those contributions, but minus investment fees and administrative charges applied against those contributions, shall be refunded to the participant by the board.