Working in the US with a Fiancé Visa
Since your fiancée is permitted to spend 90 days in the US with a K1 fiancé visa before your marriage, he or she may also be permitted to work during this time. However, permission to work does not automatically accompany a K-1 visa. Your fiancée must file Form I-765: Application for Employment Authorization. You must submit this specific fiancé visa to the USCIS Service Center responsible for immigration issues in your area.