In California, a compulsory cross-complaint is any claim you have against the person suing you that arises from the same transaction or occurrence as their lawsuit, and under Code of Civil Procedure Section 426.30 you have to raise it in that same case or you lose the right to bring it at all.1California Legislative Information. California Code of Civil Procedure – Compulsory Cross-Complaints The deadline is tight: the cross-complaint must be filed before or at the same time as your answer. Miss it and the claim is gone, unless you ask the court for permission to file late.
What Counts as a Related Claim
Section 426.10 defines a “related cause of action” as one arising out of the same transaction, occurrence, or series of transactions or occurrences as the plaintiff’s claims. If your claim shares a factual thread with what the plaintiff is suing you over, it is almost certainly compulsory.
California courts apply a “logical relationship” test. The claims don’t have to involve identical facts. The question is whether any factual or legal issues overlap enough that handling them separately would waste the court’s time and the parties’. In Currie Medical Specialties, Inc. v. Bowen, the court confirmed California follows the same broad logical-relationship standard used in most federal courts.2Justia Law. Currie Medical Specialties, Inc. v. Bowen (1982)
Courts read the requirement expansively. In Align Technology, Inc. v. Tran, the Court of Appeal barred a party from asserting claims in a new lawsuit because they were logically related to a cross-complaint filed in earlier litigation and should have been raised then.3FindLaw. Align Technology, Inc. v. Bao Tran When in doubt, treat the claim as related and put it in.
When the Compulsory Rule Doesn’t Apply
Section 426.30(b) sets out two situations where the rule drops away:
- The court hearing the plaintiff’s case lacks personal jurisdiction over you for the related claim.
- You never filed an answer. If the case ended on a demurrer or by default, the compulsory obligation never attached.1California Legislative Information. California Code of Civil Procedure – Compulsory Cross-Complaints
Section 426.40 adds a related exception: if the claim can’t be resolved without bringing in a third party the court has no jurisdiction over, you aren’t barred from raising it later.
Two other boundaries are worth being clear about. The compulsory rule covers only related claims against the plaintiff. A claim against a co-defendant or a new third party can be brought as a cross-complaint, but if you don’t bring it, you can still sue separately later. The same is true of an unrelated claim against the plaintiff: you may include it, but nothing is forfeited if you don’t.
The Filing Deadline
Under Section 428.50, a cross-complaint against the party who sued you must be filed before or at the same time you file your answer.4California Legislative Information. California Code of Civil Procedure Section 428.50 That is a shorter window than many defendants expect. By the time you have read the complaint, worked out your defenses, and drafted the answer, the cross-complaint has to be ready alongside it.
Cross-complaints against anyone other than the plaintiff get a more generous deadline. They can be filed any time before the court sets a trial date. After either deadline passes, you need the court’s permission to file.4California Legislative Information. California Code of Civil Procedure Section 428.50
Because the compulsory deadline runs with the answer, start evaluating potential cross-claims the day you are served, not after the answer is drafted. Waiting compresses an already tight window.
What Happens If You Don’t File
Section 426.30(a) permanently bars you from asserting a related claim against the plaintiff in any later lawsuit if you failed to raise it in the current one and never got leave of court to file late.1California Legislative Information. California Code of Civil Procedure – Compulsory Cross-Complaints This is a full forfeiture, not a procedural penalty you can work around.
The bar works alongside res judicata. Once the original lawsuit reaches final judgment, every related claim that should have been raised is treated as resolved, even though no one ever litigated it. A defendant with a strong breach-of-contract claim who stays silent cannot refile it afterward, no matter how clear the evidence. Align Technology illustrates the point: the court dismissed claims on their face because they should have been asserted in a prior cross-complaint.3FindLaw. Align Technology, Inc. v. Bao Tran
Filing Late With the Court’s Permission
If the deadline has already passed, Section 426.50 is the provision to know. It lets a party who failed to file a compulsory cross-complaint, whether through oversight, mistake, neglect, or any other reason, ask the court for leave to file at any point during the case. The statute directs courts to grant these requests liberally so claims aren’t permanently lost, provided the party is acting in good faith.5California Legislative Information. California Code of Civil Procedure Section 426.50
Good faith is the whole game. In Silver Organizations Ltd. v. Frank, the Court of Appeal held that a motion for leave to file a late cross-complaint must be granted unless the opposing party shows bad faith, and defined bad faith narrowly. Carelessness isn’t enough. Poor judgment isn’t enough. Bad faith requires a deliberate, dishonest intent to mislead the court or gain an unfair advantage.6Justia Law. Silver Organizations Ltd. v. Frank (1990) Forgetting, being disorganized, or not knowing the rule generally won’t sink the motion.
Still, leaning on Section 426.50 is a last resort, not a plan. A motion costs time and money, delays the case, and leaves open the small chance the court finds bad faith. If you realize after filing your answer that you have a related claim, move quickly. The longer the delay, the harder it gets to show good faith, even under the liberal standard the statute requires.
Compulsory vs. Permissive Cross-Complaints
Section 428.10 defines what a cross-complaint can include at all. A defendant can assert any claim against the party who sued them, related or not. A defendant can also pull in people who aren’t yet parties, as long as the claim arises from the same events or involves the same property or controversy at issue in the case.7California Legislative Information. California Code of Civil Procedure Section 428.10
Only one category of these is compulsory: related claims against the plaintiff. Everything else is permissive. The practical consequence for planning is simple. Focus first on identifying every factually related claim you have against the plaintiff, because those are the ones that vanish if you miss the deadline. Unrelated claims and claims against other parties can wait if timing or strategy calls for it, but the compulsory claims cannot.