(a)Priority date. (1) The filing date for a Schedule A occupation or sheepherders is the date the application was dated by the Immigration Officer. (2) The filing date, established under § 656.17(c) , of an approved labor certification may be used as a priority date by the Department of Homeland Security and the Department of State, as appropriate. (b)Expiration of labor certifications. For certifications resulting from applications filed under this part and 20 CFR part 656 in effect prior to March