California Code, Code of Civil Procedure - CCP § 472a

(a) A demurrer is not waived by an answer filed at the same time.

(b) Except as otherwise provided by rule adopted by the Judicial Council, if a demurrer to a complaint or to a cross-complaint is overruled and there is no answer filed, the court shall allow an answer to be filed upon such terms as may be just. If a demurrer to the answer is overruled, the action shall proceed as if no demurrer had been interposed, and the facts alleged in the answer shall be considered as denied to the extent mentioned in Section 431.20.

(c) Subject to the limitations imposed by subdivision (e) of Section 430.41, if a demurrer is sustained, the court may grant leave to amend the pleading upon any terms as may be just and shall fix the time within which the amendment or amended pleading shall be filed. If a demurrer is stricken pursuant to Section 436 and there is no answer filed, the court shall allow an answer to be filed on terms that are just.

(d) If a motion to strike is granted pursuant to Section 436, the court may order that an amendment or amended pleading be filed upon terms it deems proper. If a motion to strike a complaint or cross-complaint, or portion thereof, is denied, the court shall allow the party filing the motion to strike to file an answer.

(e) If a motion to dismiss an action pursuant to Article 2 (commencing with Section 583.210) of Chapter 1.5 of Title 8 is denied, the court shall allow a pleading to be filed.