The Transportation, Housing and Urban Development, and Related Agencies (THUD) appropriations subcommittees are charged with drafting bills to provide annual appropriations for the Department of Transportation (DOT), the Department of Housing and Urban Development (HUD), and six small related agencies. Title I of the annual THUD appropriations bill funds DOT. The department is primarily a grant-making and regulatory organization. Its programs are organized roughly by mode of transportation, providing grants to state and local government agencies to support the construction of highways, transit, and intercity passenger rail infrastructure, while overseeing safety in the rail, public transportation, commercial trucking and intercity bus, and maritime industries. The Federal Aviation Administration (FAA) is exceptional among DOT's large sub-agencies in that the largest portion of its budget is not for grants but for operating the U.S. air traffic control system. In support of that task, it employs over 80% of DOT's total workforce, roughly 46,000 of DOT's approximately 56,000 employees. Title II of the annual THUD appropriations bill funds HUD. The department's programs are primarily designed to address housing problems faced by households with very low incomes or other special housing needs. These include several programs of rental assistance for persons who are poor, elderly, and/or have disabilities. Three rental assistance programs—Public Housing, Section 8 Housing Choice Vouchers, and Section 8 project-based rental assistance—account for the majority of the department's funding. Two flexible block grant programs—the HOME Investment Partnership Program and Community Development Block Grants (CDBG)—help communities finance a variety of housing and community development activities designed to serve low-income families. Other, more specialized grant programs help communities meet the needs of homeless persons, including those with AIDS. HUD's Federal Housing Administration (FHA) insures mortgages made by lenders to home buyers with low down payments and to developers of multifamily rental buildings containing relatively affordable units. Title III of the THUD appropriations bill funds a collection of agencies involved in transportation or housing and community development. They include the Access Board, the Federal Maritime Commission, the National Transportation Safety Board, the Amtrak Office of Inspector General (IG), the Neighborhood Reinvestment Corporation (often referred to as NeighborWorks), the U.S. Interagency Council on Homelessness, and the costs associated with the government conservatorship and regulation of the housing-related government-sponsored enterprises, Fannie Mae and Freddie Mac. Most of the programs and activities in the THUD bill are funded through regular annual appropriations , also referred to as discretionary appropriations. This is the amount of new funding allocated each year by the appropriations committees. Appropriations are drawn from the general fund of the Treasury. For some accounts, the appropriations committees provide advance appropriations , or regular appropriations that are not available until the next fiscal year. In some years, Congress will also provide emergency appropriations , usually in response to disasters. These funds are sometimes provided outside of the regular appropriations acts—often in emergency supplemental spending bills—generally in addition to regular annual appropriations. Although emergency appropriations typically come from the general fund, they may not be included in the discretionary appropriation total reported for an agency. Most of the Department of Transportation's budget is in the form of contract authority . Contract authority is a form of mandatory budget authority based on federal trust fund resources, in contrast to discretionary budget authority, which is based on resources in the general fund. Contract authority controls spending from the Highway Trust Fund and the Airport and Airway Trust Fund. When the Appropriations Committee subcommittees are given their 302(b) allocations, those figures include only net discretionary budget authority (nonemergency appropriations, less any offsets and rescissions); contract authority from trust funds is not subject to that limitation. This can lead to confusion when comparing totals, as the total annual discretionary budget authority for THUD is typically around half of the total funding provided in the bill, with the remainder made up of mandatory contract authority. Congressional appropriators are generally subject to limits on the amount of new nonemergency discretionary funding they can provide in a year. One way to stay within these limits is to appropriate no more than the allocated amount of discretionary funding in the regular annual appropriations act. Another way is to find ways to offset a higher level of discretionary funding. A portion of the cost of regular annual appropriations for the THUD bill is generally offset in two ways. The first is through rescissions , or cancellations of unobligated or recaptured balances from previous years' funding. The second is through offsetting receipts and collections , generally derived from fees collected by federal agencies. Table 1 shows funding trends for DOT and HUD over the period FY2009-FY2015, omitting emergency funding and other supplemental funding. The purpose of Table 1 is to indicate trends in the funding for these agencies; thus emergency supplemental appropriations are not included in the figures. Table 2 provides a time line of legislative action on the FY2016 THUD appropriations bill. The annual budget resolution provides a budgetary framework within which Congress considers legislation affecting spending and revenue. It sets forth spending and revenue levels, enforced by the rules of each chamber, including spending allocations to House and Senate Appropriations Committees. After the House and Senate Appropriations Committees receive their discretionary spending allocations from the budget resolution (referred to as 302(a) allocations), they divide their allocations among their 12 subcommittees, each of which is responsible for one of the 12 regular appropriations bills. The allocations to each of the subcommittees are referred to as 302(b) allocations. The FY2016 budget resolution was agreed to by the House on April 30, 2015, and the Senate on May 6, 2015 ( H.Con.Res. 27 and S.Con.Res. 11 ). It set an overall base discretionary spending limit of $1.017 trillion for FY2016, an increase from the FY2015 level of $1.014 trillion and consistent with the current statutory spending limits under the Budget Control Act, as amended. The current Section 302(b) allocation for the Senate THUD subcommittee is $376 million more than that provided for the House subcommittee. This difference creates an additional difficulty in reaching agreement on a final FY2016 THUD appropriation level. Table 3 shows the discretionary funding provided for THUD in FY2015, the Administration request for FY2016, and the amount allocated by the House and Senate Appropriations Committees to the THUD subcommittees. Table 4 lists the total funding provided for each of the titles in the bill for FY2015 and the amount requested for that title for FY2016. As discussed earlier, much of the funding for this bill is in the form of contract authority, a type of mandatory budget authority. Thus, the discretionary funding provided in the bill is only about half of the total funding provided in this bill. As shown in Table 4 , the President's FY2016 budget requested $134.7 billion for the programs in the THUD bill, $27.4 billion more than appropriated for THUD in FY2015. Most of this increase was for highway, transit, and rail funding under the Administration's surface transportation reauthorization proposal; the request for DOT is $22 billion over FY2015. The request for HUD is $5 billion more than provided in FY2015, but $1.1 billion of that increase reflects a decline in savings available from offsetting receipts. The House-passed H.R. 2577 provides a total of $108.7 billion for THUD in FY2016. While this appears to be $1.5 billion over the net budgetary resources amount provided in FY2015, after accounting for a projected $1.1 billion reduction in offsetting receipts to HUD in FY2016 and the effects of $400 million in rescissions of funding in the FY2015 bill, the actual amount of new funding recommended in the House bill is virtually identical to the FY2015 level. The Senate-reported H.R. 2577 recommends $109.1 billion for THUD; after accounting for the differences in rescissions and offsetting receipts in FY2015, this represents an increase of less than 1% over FY2015 funding. This situation is explored further in the next section of this report and Table 5 . In the case of the THUD bill, net discretionary budget authority (which is the level of funding measured against the 302(b) allocation) is not the same as the amount of new discretionary budget authority made available to THUD agencies, due to budgetary savings available from rescissions and offsets. Each dollar available to the subcommittees in rescissions and offsets enables the subcommittee to provide funding that does not count against the 302(b) level. As shown in Table 5 , in FY2015, due to rescissions and offsets, the THUD subcommittees were able to provide $10.1 billion in discretionary appropriations to THUD agencies above the net discretionary budget authority level. The amount of these "budget savings" can vary from year to year, meaning that the "cost" in terms of 302(b) allocation of providing the same level of appropriations may vary as well. Due to a $1.1 billion reduction in offsetting collections in FY2016 compared to FY2015, it "cost" the House THUD subcommittee an additional $1.1 billion in discretionary funding in FY2016 to provide the same level of total funding as provided in FY2015, all else being equal. Combined with a decrease in rescissions in their FY2016 proposal, the House THUD subcommittee's $1.5 billion increase in 302(b) allocation over THUD's net FY2015 level ends up as a $25 million increase. And since the subcommittee also proposed reducing the mandatory funding level by $25 million, the net change for FY2016 becomes zero.