CA AB43

Eliminates the 20% interim greenhouse gas emissions reduction target for building materials and establishes a single 40% net reduction target by December 31, 2035, with implementation beginning no sooner than January 1, 2027 and two years after baseline establishment.

Authorizes the State Air Resources Board to establish an optional embodied carbon trading system for building materials, with integration into the measuring framework by December 31, 2026 and implementation on or after January 1, 2029.

Changes baseline calculation to be based on industry average environmental product declarations from 2026 or most relevant available data determined by the state board, rather than a specific 2026 report.

Removes the requirement for a formal technical advisory committee and instead requires the state board to consult with experts including manufacturers, builders, and design professionals on carbon reduction methods.

Exempts violations from criminal penalties and limits enforcement to civil penalties under Section 42402, with enhanced penalties only for violations showing disregard, extreme negligence, or deceit.