Eliminates and limits many federal supports for fossil fuels: it defines "fossil fuel," ends or restricts royalty reliefs and subsidies, bars federal funding for many fossil‑fuel projects across multiple agencies and programs, and changes liability and lender‑exclusion rules. It also makes large tax‑code changes that reduce or remove tax benefits for oil, gas, and mining activities, repeals or undoes recent statutory provisions that supported fossil‑fuel development, and requires new subsidy determinations and reports by Treasury and the Secretary of the Treasury. Many prohibitions and changes take effect on or after enactment, while several major tax changes do not apply until after December 31, 2025, and some provisions become effective when agencies publish determinations or reports.