What if my deadline to respond to a California lawsuit has already passed?

The first thing to check is the court's online register of actions to determine whether a default has actually been entered against you yet. If nothing has been entered, you can frequently still file your response even though you're technically past the original deadline.

If a default has already been entered, your path forward is a formal motion to set aside that default under Code of Civil Procedure section 473, and there's an outer time limit of six months from when the default was entered to bring that motion. Whether relief is granted often depends on whose mistake caused the missed deadline, courts treat this as close to automatic when an attorney's own error caused the problem, but treat it as more genuinely discretionary when the defendant's own mistake was the cause.