The California 20-day preliminary notice

If you’ve heard the term “20-day notice” on a job site, it’s just another name for California’s preliminary notice. The “20-day” part refers to the deadline to serve it. Here ’s what the term means and why the timing is everything.

Why “20-day”?

California requires the notice to be served within 20 days of first furnishing labor or materialsto a project (Cal. Civ. Code § 8204). That deadline is where the nickname comes from — there’s no separate document called a “20-day notice.” It’s the same preliminary notice that protects your mechanics lien rights.

When does the 20 days start?

The clock starts the first day you actually furnish labor or materials — your first day on site or first delivery — not the day you sign the contract or send an invoice. Because the 20 days are calendar days, weekends and holidays count. Find your exact date with the preliminary notice deadline calculator.

What if I’m past 20 days?

Serve it anyway. A late notice still protects the work you furnished in the 20 days before you serve it and everything afterward — only earlier work falls outside the protection. A late notice almost always beats no notice.

This page is general information, not legal advice, and does not create an attorney–client relationship. California lien and notice deadlines are strict and fact-specific — “completion” alone can be triggered by actual completion, the owner’s occupancy or use, or a 60-day cessation of labor. Notice Harbor is not a law firm. Confirm any deadline that matters to your claim with a licensed California construction attorney.