The SEMI Investment Act expands the federal advanced manufacturing investment tax credit to include materials used in semiconductor production. Currently, the credit covers semiconductor manufacturing facilities and equipment, but this bill adds a new category for semiconductor materials—both those physically incorporated into chips (like substrates and bonding materials) and specialized materials used in production but not incorporated into the final product (like processing chemicals and photolithography materials). The legislation directs the Treasury Secretary, working with the Commerce Department, to publish a list of qualifying materials within 180 days of enactment and update it annually, while also allowing companies to petition for rulings on materials not yet listed. The tax credit expansion applies to property placed in service after the bill becomes law and is designed to strengthen U.S. domestic semiconductor manufacturing by reducing investment costs for companies producing these essential materials and equipment.