California Code, Revenue and Taxation Code - RTC § 23101

(1) The taxpayer is organized or commercially domiciled in this state.

(2) Sales, as defined in subdivision (e) or (f) of Section 25120 as applicable for the taxable year, of the taxpayer in this state exceed the lesser of five hundred thousand dollars ($500,000) or 25 percent of the taxpayer's total sales. For purposes of this paragraph, sales of the taxpayer include sales by an agent or independent contractor of the taxpayer. For purposes of this paragraph, sales in this state shall be determined using the rules for assigning sales under Sections 25135 and 25136, and the regulations thereunder, as modified by regulations under Section 25137.

(3) The real property and tangible personal property of the taxpayer in this state exceed the lesser of fifty thousand dollars ($50,000) or 25 percent of the taxpayer's total real property and tangible personal property. The value of real and tangible personal property and the determination of whether property is in this state shall be determined using the rules contained in Sections 25129 to 25131, inclusive, and the regulations thereunder, as modified by regulation under Section 25137.

(4) The amount paid in this state by the taxpayer for compensation, as defined in subdivision (c) of Section 25120, exceeds the lesser of fifty thousand dollars ($50,000) or 25 percent of the total compensation paid by the taxpayer. Compensation in this state shall be determined using the rules for assigning payroll contained in Section 25133 and the regulations thereunder, as modified by regulations under Section 25137.

(c)(1) The Franchise Tax Board shall annually revise the amounts in paragraphs (2), (3), and (4) of subdivision (b) in accordance with subdivision (h) of Section 17041.

(2) For purposes of the adjustment required by paragraph (1), subdivision (h) of Section 17041 shall be applied by substituting “2012” in lieu of “1988.”