Laid-off techies invoke old law – Tech News – [The WARN Act] requires companies with more than 100 workers to give employees at least 60 days notice of a plant closing or mass layoffs. A plant closing is defined as the shutdown of a single site in which 50 or more employees lose their jobs. Mass layoffs occur when a company lets go 500 workers over 30 days, or 33 percent of the work force, if that means at least 50 people.