California Code, Family Code - FAM § 2336

(a) No judgment of dissolution or of legal separation of the parties may be granted upon the default of one of the parties or upon a statement or finding of fact made by a referee;  but the court shall, in addition to the statement or finding of the referee, require proof of the grounds alleged, and the proof, if not taken before the court, shall be by affidavit. In all cases where there are minor children of the parties, each affidavit or offer of proof shall include an estimate by the declarant or affiant of the monthly gross income of each party. If the declarant or affiant has no knowledge of the estimated monthly income of a party, the declarant or affiant shall state why he or she has no knowledge. In all cases where there is a community estate, each affidavit or offer of proof shall include an estimate of the value of the assets and the debts the declarant or affiant proposes to be distributed to each party, unless the declarant or affiant has filed, or concurrently files, a complete and accurate property declaration with the court.

(b) If the proof is by affidavit, the personal appearance of the affiant is required only when it appears to the court that any of the following circumstances exist:

(c) An affidavit submitted pursuant to this section shall contain a stipulation by the affiant that the affiant understands that proof will be by affidavit and that the affiant will not appear before the court unless so ordered by the court.