National Disaster Safety Board Act of 2021 This bill provides funding for and establishes within the executive branch a National Disaster Safety Board to study and make recommendations concerning the underlying causes of disaster-related fatalities and property damage. Specifically, the board shall review and establish the facts, circumstances, and cause or probable cause of the loss of life, human injury, and economic injury due to a natural hazard with 10 or more fatalities. The bill defines natural hazard to mean a major disaster that is naturally occurring, to include any naturally occurring heat wave or wildfire, and to exclude a technological disaster. The Government Accountability Office shall audit the board at least once every two years.