California Code, Revenue and Taxation Code - RTC § 19144

(a)(1) The amount of the installment which would be required to be paid if the estimated tax were equal to the applicable percentage of the tax shown on the return for the taxable year, or (2) in the case of the tax imposed by Article 3 (commencing with Section 23181) of Chapter 2 of Part 11 an amount equal to the applicable percentage of the lesser of the tax computed at the rate provided by Section 19024 (but otherwise on the basis of the facts shown on the return and the law applicable to the taxable year), or the tax shown on the return for the taxable year as prescribed by Section 19021, or (3) if no return was filed, the applicable percentage of the tax for that year, over

(1) For taxable years beginning before January 1, 1998, 95 percent.

(2) For taxable years beginning on or after January 1, 1998, 100 percent.