Three agencies (Empower, Contra Costa County Employees' Retirement Association, and the Social Security Administration) partnered to educate members. All questions concerning eligibility, plan coverage and rates should be directed to the Contra Costa County Benefits Office at.As long as you are eligible for retiree benefits and fill out the "Authorization for. Workshops fill up fast. Employees are strongly encouraged to enroll in Medicare Part B three months prior to retirement (if eligible). We are pleased to offer 403(b) and 457 plan options to eligible employees in order to help save for retirement. The CORE Plan helps Massachusetts nonprofit employees save and invest for a financially secure retirement. And does not dispose of each spouse's interest in the employee benefit plan.