Members eligible for the alternative formula may retire at age 50 with 25 years of service, or at age 55 with 20 years of service. A new retiree cannot work for any IMRF employer for at least 60 days.The special rule lets us pay a full Social Security check for any whole month we consider you retired, regardless of your yearly earnings. (c) Rule of 80 - Early retirement without discount. To be eligible for a TRS retirement annuity, the Illinois Pension Code requires you to terminate active service as a teacher. When am I eligible to retire? Sometimes health problems force people to retire early. If you can't work because of health problems, consider applying for Social Security disability benefits. Employers tell us this program lets them provide retirement savings to their employees in a manageable way.