Disaster Management Costs Modernization Act This bill authorizes the use of excess funds for management costs for certain disaster recovery projects. Specifically, excess funds for management costs made available to a grantee or subgrantee may be used for activities associated with building capacity to respond to or recover from incidents. Such funds may also be used to provide such assistance, including for providing training and other activities associated with any major disaster or emergency declaration, or to otherwise prepare for such an incident.