Retirerment

In 1990, I retired from the USSS/UD with 30 years of federal service. In From 1990 until 12/2004 I was employed by the VA. Could someone tell me which retirement I should be retired under. There is a problem between the CSRS and the SSA. Within 3 years, I received three different decisions. Who is the ultimate source?

Try Dept of Labor

Thank You!