Under federal law, local governments (usually counties) are compensated through various programs for reductions to their property tax bases due to the presence of most federally owned land. These lands cannot be taxed, but may create a demand for services such as fire protection, police cooperation, or longer roads to skirt the federal property. Some compensation programs are run by specific agencies and apply only to that agency's land. The most widely applicable program, administered by the Department of the Interior (DOI), is called "Payments in Lieu of Taxes" (PILT, 31 U.S.C. §§6901-6907). Under the statute, eligible lands consist of those in the National Park System, National Forest System, or Bureau of Land Management; lands in the National Wildlife Refuge System if they are withdrawn from the public domain; lands dedicated to the use of federal water resources development projects; dredge disposal areas under the jurisdiction of the U.S. Army Corps of Engineers; lands located in the vicinity of Purgatory River Canyon and Piñon Canyon, Colorado, that were acquired after December 31, 1981, to expand the Fort Carson military reservation; lands on which are located semi-active or inactive Army installations used for mobilization and for reserve component training; and certain lands acquired by DOI or the Department of Agriculture under the Southern Nevada Public Land Management Act (P.L. 105-263). This report addresses only the PILT program administered by DOI. The authorized level of PILT payments is calculated under a complex formula. No precise dollar figure can be given in advance for each year's PILT authorized level. Five factors affect the calculation of a payment to a given county: the number of acres eligible for PILT payments, the county's population, payments in prior years from other specified federal land payment programs, state laws directing payments to a particular government purpose, and the Consumer Price Index as calculated by the Bureau of Labor Statistics. Before 2008, annual appropriations were necessary to fund PILT. However, beginning with the FY2008 payment and continuing through FY2012, a provision in P.L. 110-343 for mandatory spending ensured that all counties would receive 100% of the authorized payment. P.L. 112-141 extended mandatory spending to FY2013, though there was a later sequestration of 5.1% for that year. PILT's mandatory spending was renewed for another year in P.L. 113-79, resulting in an FY2014 payment of $436.9 million. As yet, Congress has not passed a measure for the FY2015 payment, normally expected to be dispersed in June 2015. However, the House amended H.R. 3979 to include the National Defense Authorization Act. The amendment included a provision (Section 3096) for $70 million in mandatory spending for PILT. If enacted, this amount would provide roughly 16% of full funding, or perhaps less, depending on any increase in the formula-based authorized amount. Supporters of PILT are expected to seek other funding in addition to this amount. Over the next few years, the broader debate for Congress might then be summarized as three decisions: (1) whether to approve full funding of PILT through future extensions of mandatory spending (either temporary or permanent); (2) whether instead to reduce the payments, perhaps through the annual appropriations process or by changing the PILT formula; and (3) whether to add or subtract any lands to the list of those now eligible for PILT payments.