December 17, 2018 UPDATE: Congressional negotiations on federal spending for the remainder of FY 2019 remain very active. If Congress and the President can’t come to an agreement on a spending bill or continuing resolution by midnight December 21, 2018, approximately 25 percent of government functions will shut down. When it comes to immigration, agencies that would be impacted by a government shutdown include the Department of Homeland Security and its immigration-related components (CBP, ICE, USCIS, CIS Ombudsman), the Department of Justice (EOIR), and the Department of State.
Note, however, that the Department of Labor (DOL) would not be impacted by a government shutdown. On September 28, 2018, President Trump signed a minibus appropriations bill funding DOL through the end of September 30, 2019.
Source: AILA Doc. No. 17042640.