Tool: The Preliminary 20-Day Notice Construction projects face all sorts of issues, not the least of which is payment to subcontractors, material suppliers, and general contractors. Failing to serve a preliminary 20-day notice, as required by California law, can leave you unpaid on troubled projects. Here’s what you need to know to protect your payment. The preliminary 20-day notice informs property owners, direct contractors, and construction lenders that you will provide, or have provided, labor,