20 CFR § 639.10 - When may notice be extended?
Additional notice is required when the date or schedule of dates of a planned plant closing or mass layoff is extended beyond the date or the ending date of any 14-day period announced in the original notice as follows:
(a) If the postponement is for less than 60 days, the additional notice should be given as soon as possible to the parties identified in § 639.6 and should include reference to the earlier notice, the date (or 14-day period) to which the planned action is postponed, and the reasons for the postponement. The notice should be given in a manner which will provide the information to all affected employees.
(b) If the postponement is for 60 days or more, the additional notice should be treated as new notice subject to the provisions of §§ 639.5, 639.6 and 639.7 of this part. Rolling notice, in the sense of routine periodic notice, given whether or not a plant closing or mass layoff is impending, and with the intent to evade the purpose of the Act rather than give specific notice as required by WARN, is not acceptable.