Broadwell was promoted to lieutenant colonel in the Army Reserves last August. But Army spokesman George Wright says that was reversed early this month and will be pending for as long as she is under investigation.
Investigators have been looking since November into whether Broadwell had classified information in her home without permission.
Under Army rules, a promotion can be delayed if new information about a person comes to light within six months of the promotion. Investigators have said they believe materials found in her home were gathered while she was researching a biography on Petraeus, a retired general and former commander in Afghanistan.