The Investing in State Energy Act of 2026 speeds up how quickly the federal government distributes money to states and tribes for energy efficiency and renewable energy projects. The bill requires the Department of Energy to release application guidance and publish funding allocations within 60 days of funds becoming available, and to distribute approved funds to states within 30 days of receiving completed applications. This affects states, Indian tribes, and other recipients of assistance through two major federal programs: the Weatherization Assistance Program and the State Energy Program. The legislation authorizes $500 million in existing funding for these programs plus an additional $100 million annually for fiscal years 2027 through 2031. By imposing these strict timelines, the bill aims to help states and communities implement energy efficiency and renewable energy projects more quickly without delays in the federal funding process.