Cal. RTC § 19064

(a) If any person initiates a motion to quash a subpoena, as provided by Sections 7465 to 7476, inclusive, of the Government Code, and that person is the person with respect to whose liability the subpoena is issued (or is the agent, nominee, or other person acting under the direction or control of that person), then the running of any period of limitations under Section 19057 (relating to deficiency assessments), Section 19087 (relating to false or fraudulent returns), or Section 19704 (relating to criminal prosecutions) with respect to that person shall be suspended for the period during which a proceeding, and appeals therein, with respect to the enforcement of the subpoena is pending.

(b) In the absence of the resolution of the subpoenaed person’s response to a subpoena issued under Section 19504 (power of examination), the running of any period of limitations under Section 19057 (relating to deficiency assessments), Section 19087 (relating to false or fraudulent returns), or Section 19704 (relating to criminal prosecutions) with respect to any person whose liability the subpoena was issued (other than a person taking action as provided by subdivision (a)) shall be suspended for the period beginning on the date which is six months after the service of the subpoena and ending with the final resolution of that response.

(c) The amendments made by the act adding this subdivision are operative for any subpoena served after the effective date of the act adding this subdivision.