Yes, you may require that employees participate in counseling before listing their homes, provided this is written into your agency's relocation policy. This is a common practice in the private sector. Please note, however, that this may exclude from your homesale program any employee who lists their home before the relocation travel authorization is approved. If you choose to make this part of your agency policy, you should make a major, ongoing effort to inform as many of your potential transferees as possible of this policy.
41 C.F.R. §302-12.109