If, in the opinion of the board or the person designated by it, a claim as presented fails to comply substantially with the requirements of Sections 910 and 910.2, or with the requirements of a form provided under Section 910.4 if a claim is presented pursuant thereto, the board or the person may, at any time within 20 days after the claim is presented, give written notice of its insufficiency, stating with particularity the defects or omissions therein. The notice shall be given in the manner prescribed by Section 915.4. The board may not take action on the claim for a period of 15 days after the notice is given.
Ca. Gov. Code § 910.8