Synopsis As Introduced Amends the Illinois Municipal Retirement Fund (IMRF) Article of the Illinois Pension Code. Requires the Fund, by rule, to establish a defined contribution benefit plan. Requires the plan to be qualified under the Internal Revenue Code of 1986 and to authorize each participating municipality and participating instrumentality to (i) require participation in the plan by any person who first becomes its employee on or after January 1, 2012, (ii) define benefit levels and employer contributions as it sees fit, (iii) make benefit changes as it deems appropriate, and (iv) otherwise administer the plan. Provides that participating municipalities and instrumentalities must elect to participate in the plan by no later than January 1, 2012. Amends the State Mandates Act to require implementation without reimbursement. Effective immediately.