Disaster Management Costs Modernization Act

This bill amends the Robert T. Stafford Disaster Relief Act to allow federal grantees and subgrantees to reuse excess funds originally allocated for management costs after a disaster. Specifically, it defines "excess funds for management costs" as the difference between authorized management costs and actual spending, then permits the President to make these funds available for disaster preparedness, recovery, mitigation activities, or management costs related to declared disasters. The funds can be used for 5 years after being made available and directly affect state/local governments and organizations receiving federal disaster relief under sections 403, 404, 406, 407, or 502. It does not change overall funding levels but streamlines how unused management cost funds are reallocated for future disaster needs.