The California General Corporation Law defines "foreign association" as a business organization organized as a trust under the laws of a foreign jurisdiction. Cal. Corp. Code § 170. For purposes of Chapter 21 of the GCL, a "foreign corporation" includes a foreign association, unless otherwise provided. Cal. Corp. Code § 171. Consequently, a foreign business trust that transacts intrastate business in California must obtain a certificate of qualification from the California Secretary of State. Cal. Corp. Code § 2105(a).
Foreign corporations that have qualified to transact intrastate business in California must file a Statement of Information with the California Secretary of State within 90 days of registering with the California Secretary of State, and every year thereafter during a specific 6-month filing period based on the original registration date. Seemingly, this requirement would pertain to a foreign business trust as well. Section 2117(a) of the Corporations Code, however, specifically excludes foreign associations from the requirement to file a statement of information.
If a foreign association may be required to file an amended statement and designation if (i) it changes its name, the address of its principal office in California, the address of its principal executive office or its agent for service of process; or (ii) the stated address of any natural person designated as agent is changed. Cal. Corp. Code § 2107(b). The form of amended statement of designation is available here.