Is this hospital is open for all civil people or only for Military service holder/ Ex-military. Can anyone go to there for treatment? Are they taking fees like private hospital?

Randee is correct. Civilians are treated in an emergency and billed as per usual practices.

Typically civilians are not treated here. It's not a private hospital. Active duty, retirees and dependents for sure. Possibly DoD and contractor employees but definitely call to get accurate information.

I believe Fort Belvoir is for Active and Retired Military. You could call to make sure!!