California Code, Unemployment Insurance Code - UIC § 13056

(1) Any person or employer required under the authority of this division to make a return, report, statement, or other document shall include in the return, report, statement, or other document the identifying number as may be prescribed for securing proper identification of the person.

(2) Any person with respect to whom a return, report, statement, or other document is required under the authority of this division to be made by another person shall furnish to the other person the identifying number as may be prescribed for securing his or her proper identification.

(3) Any person or employer required under the authority of this division to make a return, report, statement, or other document with respect to another person shall request from the other person, and shall include in the return, report, statement, or other document, the identifying number as may be prescribed for securing proper identification of the other person.

(b)(1) Except as provided in paragraph (2), a return or report of any person with respect to his or her liability for tax, or any statement or other document in support thereof, shall not be considered for purposes of paragraphs (2) and (3) of subdivision (a) as a return, report, statement, or other document with respect to another person.

(2) For purposes of paragraphs (2) and (3) of subdivision (a), a return or report of an estate or trust with respect to its liability for tax, and any statement or other document in support thereof, shall be considered as a return, report, statement, or other document with respect to each beneficiary of the estate or trust.