Casualty Assistance Reform Act of 2021 This bill requires the Department of Defense (DOD) to establish the Casualty Assistance Reform Working Group to, among other duties, create standards and training for casualty assistance officers of the Armed Forces. Generally, a casualty assistance officer supports and assists the next of kin after they have been notified of a casualty. The bill also requires DOD to publish an interim rule to establish standard definitions of gold star family and gold star survivor .