Everything You Want to Know About CSRS Federal Retirement (OPM.gov)
Article Excerpt: "...The Civil Service Retirement System (CSRS) is a defined benefit, contributory retirement system. Employees share in the expense of the annuities to which they become entitled. CSRS covered employees contribute 7, 7 1/2 or 8 percent of pay to CSRS and, while they generally pay no Social Security retirement, survivor and disability (OASDI) tax, they must pay the Medicare tax (currently 1.45 percent of pay). The employing agency matches the employee's CSRS contributions...."
Resource: www.opm.gov