Cal. RTC § 23222a

In every case in which the second or succeeding taxable years of a commencing taxpayer constitute a period of less than 12 months or in which the taxpayer does business for a period of less than 12 months during its second or succeeding taxable years, the tax for such year or years shall be measured by the income of that period or periods subject to the continuation of the prepayment procedure outlined in Section 23222. In no event shall the income of any period or periods herein described be used as the measure of the tax for the succeeding taxable year, other than the prepayment, until the last short period is succeeded by a taxable period of 12 months, in which case the income of the last short period shall, if greater than the income of the 12-month period, constitute the measure of the tax for such 12-month period.

Thereafter the procedure outlined in Section 23222, in respect of the second and third taxable years, shall apply and the taxpayer shall not be subject to the provisions of this section.

In the event that a taxpayer is dissolved or withdraws from this state while subject to the provisions of this section, its tax for the year of dissolution or withdrawal shall be measured by its net income for such year. However, in no event shall the tax be less than the minimum tax provided by Section 23153.

The provisions of this section shall be applicable only if a taxpayer commenced doing business in this state before January 1, 1972.