Legal Question in Landlord & Tenant Law in California

Any party may amend a pleading, once, as a matter of right, before the time runs to file a demurrer. (Code Civ. Proc., sect. 472.) Normally an answer can be objected to by way of demurrer. (Code Civ. Proc., sect. 430.30, subd. (a).) The time to demur to an answer is normally within ten (10) days of service. (Code Civ. Proc. sect. 430.40, subd. (b).)

Demurrers to answers are rare, and I've never seen a demurrer to an answer in an unlawful detainer case, so I believe the 10 day from service rule would apply. That 10 days would include holidays, but would be extended to the first day that the court was open if the 10 days expired on a holiday or weekend. If the court clerk rejects an amended answer, you will have to file a noticed motion seeking leave to file an amended answer, and should probably get some legal help to do so.