See also CCP section 473 for other set aside rules.
CALIFORNIA CODE OF CIVIL PROCEDURE
VARIANCE-MISTAKES IN PLEADINGS AND AMENDMENTS
Notice or motion to set aside default or default judgment and leave to defend
Code of Civil Procedure Section 473.5
(a) When service of a summons has not resulted in actual notice to a party in time to defend the action and a default or default judgment has been entered against him or her in the action, he or she may serve and file a notice of motion to set aside the default or default judgment and for leave to defend the action. The notice of motion shall be served and filed within a reasonable time, but in no event exceeding the earlier of: (i) two years after entry of a default judgment against him or her; or (ii) 180 days after service on him or her of a written notice that the default or default judgment has been entered.
(b) A notice of motion to set aside a default or default judgment and for leave to defend the action shall designate as the time for making the motion a date prescribed by subdivision (b) of Section 1005, and it shall be accompanied by an affidavit showing under oath that the party's lack of actual notice in time to defend the action was not caused by his or her avoidance of service or inexcusable neglect. The party shall serve and file with the notice a copy of the answer, motion, or other pleading proposed to be filed in the action.
(c) Upon a finding by the court that the motion was made within the period permitted by subdivision (a) and that his or her lack of actual notice in time to defend the action was not caused by his or her avoidance of service or inexcusable neglect, it may set aside the default or default judgment on whatever terms as may be just and allow the party to defend the action.