Cal. RTC § 107.3

The full cash value of leasehold estates in exempt property for the production of gas, petroleum and other hydrocarbon substances from beneath the surface of the earth and all other taxable rights to produce gas, petroleum and other hydrocarbon substances from exempt property (all of which rights are hereinafter in this section referred to as “such oil and gas interests”), is the value of such oil and gas interests, exclusive of the value of any royalties or other rights to share in production from exempt property owned by any tax-exempt entity, whether receivable in money or property and whether measured by or based upon production or income or both.

This section applies to:

(a) Such oil and gas interests created prior to the date on which the decision in De Luz Homes, Inc. v. County of San Diego (1955) 45 Cal. 2d 546, became final to which Section 107.2 of this code does not apply because said interests were extended or renewed on or before July 26, 1963.

(b) Such oil and gas interests created on or after the date on which said decision become final and on or before July 26, 1963.

This section does not, however, apply to any of such oil and gas interests extended or renewed after July 26, 1963, unless such extension or renewal is pursuant to authority in a contract, lease, statute, regulation, city charter, ordinance or other source which authority permits no reduction of the rate of royalty or other right to share in production upon the ground of an increase in the assessed valuation of such oil and gas interest. Moreover, this section does not apply to any of such oil and gas interests if the rate of royalties or other right to share in production has, prior to the effective date of this section, been reduced to adjust for the fact that certain assessors have valued such oil and gas interests without excluding the value of said royalties or other rights to share in production.