What Triggers Notice
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Mass Layoff: A covered employer must give notice if there is to be a mass layoff which does not result from a plant closing, but which will result in an employment loss at the employment site during any 30-day period for 500 or more employees, or for 50-499 employees if they make up at least 33% of the employer's active workforce. Again, this does not count employees who have worked less than 6 months in the last 12 months or employees who work an average of less than 20 hours a week for that employer. These latter groups, however, are entitled to notice (discussed later).
An employer also must give notice if the number of employment losses which occur during a 30-day period fails to meet the threshold requirements of a plant closing or mass layoff, but the number of employment losses for 2 or more groups of workers, each of which is less than the minimum number needed to trigger notice, reaches the threshold level, during any 90-day period, of either a plant closing or mass layoff. Job losses within any 90-day period will count together toward WARN threshold levels, unless the employer demonstrates that the employment losses during the 90-day period are the result of separate and distinct actions and causes.