The farm bill is an omnibus, multi-year law that governs an array of agricultural and food programs. It provides an opportunity for policymakers to periodically address a broad range of agricultural and food issue s. The farm bill has typically undergone reauthorization about every five years. In the past, farm bills have focused primarily on farm commodity program support for a handful of staple commodities—corn, soybeans, wheat, cotton, rice, dairy, and sugar. Farm bills have become increasingly expansive in their topical scope since 1973, when a nutrition title was included. Other prominent additions include conservation, horticulture, and bioenergy programs. Recent farm bills have been subject to various developments, such as insufficient votes to pass the House floor, presidential vetoes, or—as in the case of 2008 and 2014 farm bills—short-term extensions. The 2002 farm bill was the most recent to be enacted before the fiscal year expiration date for some programs. The current farm bill (the Agricultural Act of 2014, P.L. 113-79 ) has many provisions that expire in 2018. The 115 th Congress has begun but not finished a new farm bill. An initial House vote on H.R. 2 failed by vote of 198-213, but floor procedures allowed that vote to be reconsidered, and it passed by a second vote of 213-211. The Senate passed its bill as an amendment to H.R. 2 by a vote of 86-11. Conference proceedings officially began on September 5, 2018, but have not reached agreement. The timing and consequences of expiration vary by program across the breadth of the farm bill. There are two principal expiration dates: September 30 and December 31. The 2014 farm bill generally expires either at the end of FY2018 (September 30, 2018), or at the end of the 2018 crop year. Crop years vary by commodity, but the first to be affected by a new crop year is dairy, which has a 2018 crop year that ends on December 31, 2018. Expiration of a farm bill on September 30 matters for programs with fiscal year authorizations. These programs include certain nutrition, conservation, trade, and agricultural support programs (excluding the Title I commodity programs), along with many authorizations for discretionary appropriations. Although the Supplemental Nutrition Assistance Program (SNAP) has an authorization of appropriations ending on September 30, it (and other related programs in the SNAP account) can continue to operate with an appropriation. Farm commodity programs expire on a crop year. A crop year is the year in which crops are harvested and may extend into a new calendar year. In the case of dairy, the crop year is the calendar year. Following the expiration of the current farm law without replacement legislation or an extension, the first farm commodity program to be affected would be dairy, whose new crop year begins on January 1, 2019. The possible consequences of expiration include minimal disruption (if the program is able to be continued via appropriations), ceasing new activity (if its authorization to use mandatory funding expires), or reverting to permanent laws enacted decades ago (for the farm commodity programs). For example An appropriations act or a continuing resolution can continue some farm bill programs even though a n authority has expired. Programs using discretionary funding—and programs using appropriated mandatory funding such as those in the SNAP account—can continue to operate via appropriations action. Most farm bill programs with mandatory funding generally cease new operations when they expire (e.g., the Conservation Reserve Program (CRP), and Market Assistance Program (MAP)). However, existing contracts under prior-year authority could generally continue to be paid. Exceptions include SNAP and programs in the SNAP account (as discussed above), the farm commodity programs, and crop insurance (as discussed below). The mandatory farm commodity programs would begin reverting to permanent law beginning with the 2019 crop year , for which dairy is the first to be affected, beginning on January 1, 2019. However, payments for the 2018 crop year would continue to be authorized from the 2014 farm bill, including final payments for corn and soybeans that would be made as late as October 2019 after the 2018 crop's marketing year. Crop insurance is an example of a program with mandatory funding that is permanently authorized outside of the farm bill and does not expire. 9 The funding source that is authorized matters, since some programs use discretionary appropriations and some are mandatory spending. These differences affect how the farm bill is constructed under normal circumstances. They also affect what happens when the farm bill expires or if there is an extension. Farm bill programs are generally funded in two ways: 1. Discretionary authorizations. A farm bill sets the parameters for programs and authorizes them to receive funding in subsequent appropriations, but does not provide or assure actual funding. Budget enforcement is through future appropriations acts and budget resolutions. 2. Mandatory spending. A farm bill authorizes outlays and pays for them with multiyear budget estimates when the farm bill is enacted. Budget enforcement is through "PayGo" budget rules, baseline projections, and scores of the effect of proposed bills. The baseline is a projection of future federal spending on mandatory programs under current law. It is a benchmark against which proposed changes in law are measured (i.e., the score of a bill). Discretionary spending is authorized throughout the farm bill. Discretionary programs include most rural development, credit, and research programs, and some conservation and nutrition programs. Some smaller research, bioenergy, and rural development programs are authorized to receive both mandatory and discretionary funding. Most agency operations are financed with discretionary funds. SNAP—a mandatory program—also requires an appropriation and can be continued in expiration situation via appropriations action. Without a new farm bill or extension, many programs may not appear to have statutory authority to receive appropriations (an "authorization of appropriations"). However, appropriations law allows the continued operation of a program where only appropriations action has occurred. The Government Accountability Office (GAO) says there is no constitutional or statutory requirement for an appropriation to have a prior authorization. Congress distinguishes between authorizations and appropriations, but this is a congressional construct. GAO says that "the existence of a statute imposing substantive functions upon an agency that require funding for their performance is itself sufficient legal authorization for the necessary appropriations." For expired authorizations, GAO says that "appropriation of funds for a program whose funding authorization has expired ... provides sufficient legal basis to continue the program." Programs that rely on mandatory funding are perhaps the most at risk for interruption if the farm bill expires. Most farm bill programs with mandatory funding have an expiration date either on their program authority or their funding authority. These include farm commodity programs, some conservation programs, agricultural trade programs, and international food aid programs. For the most part, without reauthorization or an extension, these programs would cease to operate or undertake new activities in an expiration. Exceptions are noted above. Among the mandatory-funded programs that are usually the focus of the farm bill, there are two subcategories that may affect congressional action—some have baseline beyond FY2018 and some do not have baseline after FY2018. In an expiration, both categories of mandatory programs face similar disruption when their authorizations expire. But the difference in having or not having a baseline is important as Congress writes a farm bill or if Congress considers an extension to deal with an expiration. For example, when Congress enacted a one-year extension of the 2008 farm bill for 2013, the extension act was budget-neutral. The major programs that had baseline were extended at no additional budgetary cost. However, the subset of programs without baseline did not continue in the 2013 extension because they would have needed budgetary offsets to provide continuing funding and not increase the deficit. Providing funding for those programs without baseline would have made the extension more difficult. The current, partial expiration of the 2014 farm bill has precedent in the two most recent farm bills—the 2002 and 2008 farm bills. As the 2014 farm bill was being developed, there were two periods of expiration of the 2008 farm bill. The first was from October 1, 2012, through January 1, 2013, and the second dated from October 1, 2013, through February 6, 2014. Some programs ceased new operations, while others were able to continue. However, neither expiration lasted long enough for the farm commodity programs to revert to a "permanent law" that would have raised support prices and increased federal outlays. On the first occasion, the 2008 farm bill was extended for one year; all provisions that were in effect on September 30, 2012, were extended through FY2013 or for the 2013 crop year as applicable. Programs without baseline did not continue in FY2013 because no additional mandatory funding was provided in the extension. On the second occasion, no extension was enacted since a conference agreement was expected. The Agricultural Act of 2014 (2014 farm bill; P.L. 113-79 ) was enacted on February 7, 2014, to cover the 2014-2018 crop years and other programs through September 30, 2018. As the 2008 farm bill was being developed, the 2002 farm bill expired and portions of it were extended six times for less than a year in total. The first of those extensions continued authority for many expiring programs for about three months. Because final agreement was pending, five more extensions each covered a week to a month. With a few exceptions, these extensions continued the 2002 farm bill provisions—including the dairy and sugar programs, but not the direct, counter-cyclical, and marketing loan programs for the other supported commodities. Programs without baseline did not continue during the first part of the fiscal year because no additional mandatory funding was provided in the short term extensions. The last year for the 2014 farm bill's commodity programs is the 2018 crop year—that is, crops harvested during 2018 and marketed during the twelve months following harvest. The dairy margin protection program is the first such program that would expire, on December 31, 2018.