Cal. Rev. & Tax. Code § 17029.5

(a) The enactment of the act adding this section to the code shall not deprive any taxpayer of any carryover of a credit, excess contribution, or loss to which that taxpayer was entitled under this part, including all amendments enacted prior to January 1, 1987.
(b) The carryover of the credit, excess contribution, or loss shall be allowed to be carried forward under the act adding this section to the code for the same period of time as the taxpayer would have been entitled to carry that item forward under prior law.
(c) For purposes of applying the provisions of the act adding this section to the code, the basis or recomputed basis of any asset acquired prior to January 1, 1987, shall be determined under the law at the time the asset was acquired and any adjustments to basis shall be computed as follows:
1. (1) Any adjustments to basis for taxable years beginning prior to January 1, 1987, shall be computed under applicable provisions of this part, including all amendments enacted prior to January 1, 1987; and
2. (2) Any adjustments to basis for taxable years beginning on or after January 1, 1987, shall be computed under the applicable provisions of the act adding this section to the code.