Cal. Rev. & Tax. Code § 6375

There are exempted from the taxes imposed by this part the gross receipts from the sale of and the storage, use, or other consumption in this state of, tangible personal property made, prepared, assembled, or manufactured by organizations formed and operated for charitable purposes qualifying for the exemption provided by Section 214 known as the “welfare exemption,” which are engaged in the relief of poverty and distress, and make the sales and donations as a matter of assistance to the purchasers and donees.