Cal. Civ. Proc. Code § 2025.220
(a) A party desiring to take the oral deposition of any person shall give notice in writing. The deposition notice shall state all of the following, in at least 12-point type:
(8)
(A) A statement disclosing the existence of a contract, if any is known to the noticing party, between the noticing party or a third party who is financing all or part of the action and either of the following for any service beyond the noticed deposition: