California Code, Revenue and Taxation Code - RTC § 23151

(a) With the exception of banks and financial corporations, every corporation doing business within the limits of this state and not expressly exempted from taxation by the provisions of the Constitution of this state or by this part, shall annually pay to the state, for the privilege of exercising its corporate franchises within this state, a tax according to or measured by its net income, to be computed at the rate of 7.6 percent upon the basis of its net income for the next preceding income year, or if greater, the minimum tax specified in Section 23153.

(b) For calendar or fiscal years ending after June 30, 1973, the rate of tax shall be 9 percent instead of 7.6 percent as provided by subdivision (a).

(c) For calendar or fiscal years ending in 1980 to 1986, inclusive, the rate of tax shall be 9.6 percent.

(d) For calendar or fiscal years ending in 1987 to 1996, inclusive, and for any income year beginning before January 1, 1997, the tax rate shall be 9.3 percent.

(e) For any income year beginning on or after January 1, 1997, and before the income year identified in subparagraph (A) of paragraph (1) of subdivision (f), the tax rate shall be 8.84 percent. The change in rate provided in this subdivision shall be made without proration otherwise required by Section 24251.