California Code, Public Resources Code - PRC § 3402

There shall annually be imposed upon the person operating each oil well in this state, or owning royalty or other interests in respect to the production from the well, a charge which shall be payable to the Treasurer and which shall be computed at a uniform rate per barrel of oil produced from the well for the preceding calendar year.  The charge shall be apportioned among all of those persons in fractional amounts proportionate to their respective fractional interests in respect to the production of the well, but the whole of the charge shall be payable by the operator, who shall withhold their respective proportionate shares of the charge from the amounts otherwise payable or deliverable to the owners of royalty or other interests.  In the case of a penalty for late payment as provided in Section 3420, no apportionment shall be made.