Final answer:
An employer can request recertifications as often as necessary within the guidelines set by the applicable laws and regulations.
Step-by-step explanation:
An employer can request recertifications as often as necessary, as long as it is within the guidelines set by the applicable laws and regulations. For example, under the Worker Adjustment and Retraining Notification (WARN) Act, employers with more than 100 employees are required to provide written notice 60 days before plant closings or large layoffs. This means that employers may request recertifications if there are changes or updates to the plant closing or layoff plans within the 60-day notice period.