The Recycled Materials Attribution Act of 2026 would prohibit companies from making misleading claims about recycled content when advertising or selling products to consumers. The legislation specifically authorizes the use of "mass balance accounting," a method that tracks recycled materials through manufacturing supply chains, as a valid way to substantiate recycled content claims if certified by an independent third party. Within one year of enactment, the Federal Trade Commission would update its environmental marketing guidelines and issue new guidance to establish clear standards for accurate recycled content claims. The FTC would enforce violations as deceptive trade practices under existing law, and the bill would preempt any conflicting state or local regulations to create uniform national standards for recycled content labeling.