While about three-fourths of active federal employees are covered by the FERS system, the large majority of retirees are drawing benefits under CSRS, the older of the two systems. There are about 1.6 million CSRS retirees versus about 280,000 under FERS; similarly, there are about 590,000 CSRS survivor beneficiaries compared with about 27,000 under FERS. The average monthly benefit for CSRS retirees is about $2,600 and for FERS retirees about $950; survivor benefits average about $1,200 and $400, respectively. The difference in benefit levels reflects the less generous FERS computation; FERS was designed to produce benefits roughly equivalent to those under CSRS after taking into account Social Security coverage and enhanced TSP benefits.