As required by the Climate Commitment Act (CCA), Ecology is investigating the option of linking Washington’s Cap-and-Invest Program carbon market with the California-Québec carbon market. In a linked Cap-and-Invest Program, Washington’s carbon market would combine with the joint California-Québec market to create a single shared market with joint allowance auctions and a common allowance price across all jurisdictions. Allowances could be traded across jurisdictions and used to cover emissions in any of the three jurisdictions. As part of this effort, the Legislature passed legislation in 2024 modifying the CCA in ways that facilitate linkage (Engrossed Second Substitute Senate Bill 6058). This rulemaking is needed to modify Chapter 173-446 WAC and Chapter 173-441 WAC to implement these statutory changes as well as to make other changes to these rules necessary to facilitate linkage. These rule changes do not constitute linkage, nor do they require linkage or do anything that would make linkage inevitable. Additional steps would be needed, outside of the Washington rulemaking process, to establish linkage, including signing on to a linkage agreement. The Climate Commitment Act directs Ecology to consider linking Washington's Cap-and-Invest Program with other carbon markets. The law also requires Ecology to review specific criteria to ensure linkage would benefit Washington’s communities, economy, and climate goals.