Cal. Pub. Util. Code § 892.2

On or before the last day of the month following each calendar quarter, a return for the preceding quarterly period shall be filed with the State Board of Equalization in such form as the board may prescribe. A return shall be filed by every public utility gas corporation, and by every person consuming, as defined in this article, natural gas transported by a provider other than the public utility gas corporation. The return shall be signed by the person required to file the return or by his or her duly authorized agent.