CSRS and FERS employees may elect to credit NAFI service for retirement purposes under this subpart if:
    
    
        
        (a) 
         They separate for retirement on or after December 28, 2001;
     
    
        
        (b) 
         They do not otherwise qualify for immediate retirement; and
     
    
        
        (c) 
         They have enough otherwise creditable civilian service to qualify for deferred retirement.