The options include
coming to agreement on regular appropriations acts by October 1, the beginning of a new fiscal year; using one or more interim continuing resolutions (CRs) to extend temporary funding beyond the beginning of a fiscal year, until a point in time when negotiators make final decisions about full-year funding levels; or not agreeing on full-year or interim appropriations acts, resulting in a temporary funding gap and a corresponding shutdown of affected federal government activities. The criteria for determining which activities are affected are complex, as discussed later in this report. This report discusses the causes of funding gaps and shutdowns of the federal government, processes that are associated with shutdowns, and how agency operations may be affected by shutdowns. The report concludes with a discussion of potential issues for Congress. A funding gap and shutdown are distinct events, however (see Box 1 ). Experience from FY1977 to Present

Funding gaps and government shutdowns have occurred in the past when Congress and the President did not enact regular appropriations bills by the beginning of the fiscal year. Two funding gaps and corresponding shutdowns of affected activities ensued, amounting to five full days during November 1995 and 21 full days during December 1995-January 1996. Nevertheless, another relatively long funding gap began on October 1, 2013, the first day of FY2014, after funding for FY2013 expired at the end of September. A 16-full-day shutdown of affected activities followed. Subsequently, in FY2018, two brief shutdowns occurred. OMB directed agencies to execute plans for an orderly shutdown, and the Office of Personnel Management (OPM) indicated that a lapse in appropriations could affect agency operations with implications for whether employees should report to work on Saturday, January 20, 2018. These plans sometimes also have been called "contingency plans." Among other things, a shutdown plan is required to include 
a summary of agency activities that will continue and those that will cease; an estimate of the time to complete the shutdown, to the nearest half-day; the number of employees expected to be on-board (i.e., filled positions) before implementation of the plan; and the total number of employees to be retained (i.e., not furloughed), broken out into five categories of exceptions to the Antideficiency Act, including employees (1) who are paid from a resource other than annual appropriations; (2) who are necessary to perform activities expressly authorized by law; (3) who are necessary to perform activities necessarily implied by law; (4) who are necessary to the discharge of the President's constitutional duties and powers; and (5) who are necessary to protect life and property. Documents also addressed availability of government services, unemployment compensation for federal employees, union concerns, and information about past shutdowns. Effects of a Federal Government Shutdown on Government Operations

Effects of a shutdown may occur at various times, including in anticipation of a potential funding gap (e.g., planning), during an actual gap (e.g., furlough and curtailed operations), and afterwards (e.g., addressing backlogs of work). A graphical depiction of the FY1996 appropriations process, including the two funding gaps, is available in another CRS report. The FY2014 Shutdown

After the second FY1996 shutdown, no shutdowns occurred until over 17 years later, in FY2014. In this case, a funding gap began on October 1, 2013, the first day of FY2014, after funding from the previous fiscal year expired at the end of the day on September 30. The memorandum, which still was in effect for the FY1996 shutdowns and posted online by OPM as a reference for agencies for the FY2014 shutdown, explained:
Beginning [on the first day of the appropriations hiatus], agencies may continue activities otherwise authorized by law, those that protect life and property and those necessary to begin phasedown of other activities. More detailed discussion of some topics may be found in other CRS products. During the shutdown, agency contingency plans stated that several grant-related activities would be disrupted. Across the legislative branch, the impact of the FY2014 shutdown varied. The April and December 2011 releases of agency shutdown plans on the Internet—on OMB's website and on agency websites—brought a new level of transparency to agency shutdown planning. For example, when there is a gap in federal funding for state-administered programs during a federal government shutdown, states must decide whether to fill the gap with state funding to continue program operations or to cease program activities until the federal funding is restored.
When federal agencies and programs lack funding after the expiration of full-year or interim appropriations, the agencies and programs experience a funding gap. If funding does not resume in time to continue government operations, then, under the Antideficiency Act, an agency must cease operations, except in certain situations when law authorizes continued activity. Funding gaps are distinct from shutdowns, and the criteria that flow from the Antideficiency Act for determining which activities are affected by a shutdown are complex.
Failure of the President and Congress to reach agreement on full-year or interim funding measures occasionally has caused shutdowns of affected federal government activities. The longest such shutdown lasted 21 full days during FY1996, from December 16, 1995, to January 6, 1996. More recently, a relatively long funding gap commenced on October 1, 2013, the first day of FY2014, after funding for the previous fiscal year expired. Because funding did not resume on October 1, affected agencies began to cease operations and furlough personnel that day. A 16-full-day shutdown ensued, the first to occur in over 17 years. Subsequently, two comparatively brief shutdowns occurred during FY2018, in January and February 2018, respectively.
Government shutdowns have necessitated furloughs of several hundred thousand federal employees, required cessation or reduction of many government activities, and affected numerous sectors of the economy. This report discusses
causes of shutdowns, including the legal framework under which they may occur; processes related to how agencies may plan for the contingency of a shutdown; effects of shutdowns, focusing especially on federal personnel and government operations; and issues related to shutdowns that may be of interest to Congress.
This CRS report is intended to address questions that arise frequently related to the topic of government shutdowns. However, the report does not closely track developments related to the appropriations process for a given fiscal year. For links to CRS resources related to annual appropriations, see the "CRS Appropriations Status Table," at http://www.crs.gov/AppropriationsStatusTable/Index.
Additional resources related to funding gaps and shutdowns are identified below.
Agency Shutdown Plans
For links to agency shutdown plans (also sometimes called "contingency plans") of varying dates, see the Office of Management and Budget's (OMB's) website, at https://www.whitehouse.gov/omb/information-for-agencies/agency-contingency-plans/.
CRS Written Products
Listing of CRS written products related to FY2014 shutdown. For an annotated list of CRS products that relate to the FY2014 funding gap, shutdown, and related status of appropriations, see CRS Report R43250, CRS Resources on the FY2014 Funding Gap, Shutdown, and Status of Appropriations, by [author name scrubbed]. Funding gaps history. For discussion of funding gaps in recent decades and a more detailed chronology of legislative actions and funding gaps that led to the two shutdowns of FY1996 and the shutdown of FY2014, see CRS Report RS20348, Federal Funding Gaps: A Brief Overview, by [author name scrubbed]. Past government shutdowns. For an annotated list of historical documents and other resources related to past government shutdowns, see CRS Report R41759, Past Government Shutdowns: Key Resources, by [author name scrubbed] and [author name scrubbed].
CRS Services
For questions concerning the impact of a shutdown on a specific agency or program in the executive branch, legislative branch operations, or judicial branch operations,
see the contact information for CRS subject matter experts who are listed in CRS Report R41723, Funding Gaps and Government Shutdowns: CRS Experts; use the "place a request" function on the CRS website; call CRS at [phone number scrubbed]; or see the "Key Policy Staff" table at the end of this report.