Introduction

The National Defense Authorization Act (NDAA) is a policy bill typically introduced and reported each year by the House and Senate Committees on Armed Services (also known as the House Armed Services Committee, or HASC, and the Senate Armed Services Committee, or SASC). Unlike an appropriations act, the NDAA generally does not provide funding (i.e., budget authority).¹ Rather, the legislation sets policy and authorizes appropriations for the U.S. Department of Defense (DOD), nuclear weapons and reactor programs of the U.S. Department of Energy (DOE), and certain other defense-related activities.

The NDAA is a vehicle through which Congress fulfills its responsibility as mandated in Article I, Section 8, of the U.S. Constitution. This section of the Constitution provides Congress the authority to "provide for the common Defence," "raise and support Armies," "provide and maintain a Navy," and "make Rules for the ... Regulation of the land and naval Forces," among other powers.²

As an authorizing measure, the legislation establishes or amends defense programs, projects, or activities, and provides guidance on how appropriated funds are to be used in carrying out those efforts. While the NDAA does not provide budget authority, historically it has provided an indicator of congressional intent on funding for particular programs. The bill authorizes funding for DOD activities at the same level of detail at which budget authority is provided by the corresponding defense, military construction, and other appropriations acts. Despite a statutory requirement for annual authorization of appropriations for defense programs,³ the U.S. Government Accountability Office (GAO) has concluded that Congress is free to deviate from authorized amounts in subsequent appropriations.⁴ According to GAO, "If Congress appropriates money to the Defense Department in violation of 10 U.S.C. §114, there are no practical consequences. The appropriation is just as valid, and just as available for obligation, as if section 114 had been satisfied or did not exist." As defense authorization and appropriations legislation can differ on a line-item level, an authorization of appropriations in the NDAA may be considered a funding indicator rather than a floor or ceiling.⁵

The NDAA has a history of regular enactment; FY2024 marked the 63^rd consecutive fiscal year for which Congress enacted an annual defense authorization.⁶ Because of this history of regular enactment, the bill sometimes serves as a vehicle for legislation originating in committees other than HASC or SASC.⁷

This report provides an overview of defense-related funding authorizations and legislative activity on the FY2024 NDAA (i.e., Division A through Division D of P.L. 118-31). Detailed analysis of funding and policy provisions associated with individual programs, projects, and activities in the bill is beyond the scope of this report. For a list of related CRS products on the FY2024 NDAA, see Appendix C.

Bill Overview

This section of the report provides a summary of funding authorizations in the FY2024 NDAA, including elements of congressional debate on the size of the defense budget. It also provides a summary of legislative activity on the FY2024 NDAA, including certain congressional actions with respect to the House-passed, Senate-passed, and enacted versions of the bill.

Summary of Funding Authorizations⁸

The majority (96%) of funding requested in the national defense budget function for FY2024 fell within the scope of the NDAA.⁹ The national defense budget function, identified by the numerical notation 050, is one of 20 major budget functions used by the White House Office of Management and Budget (OMB) to organize budget data and the government's broadest measure of defense-related funding.¹⁰ The legislation typically authorizes discretionary funding for programs in the DOD-military subfunction (051) and atomic energy defense activities subfunction (053); and certain programs in the defense-related activities (054) subfunction.¹¹ In general, discretionary funding refers to funding provided in appropriations acts, while mandatory funding refers to funding controlled by other laws.¹² Of the $910.8 billion in total funding requested in the FY2024 President's budget for programs, projects, and activities within the national defense budget function,¹³ $874.2 billion fell within the scope of the FY2024 NDAA.¹⁴

During deliberation of the FY2024 NDAA, Congress debated whether to authorize more, the same, or less funding than the President requested for such activities. The enacted version of the legislation authorized $874.2 billion, as requested. Together with amounts for certain defense-related programs not within the purview of the legislation or requiring additional authorization, the discretionary budget authority implication of the enacted FY2024 NDAA totaled $886.3 billion—consistent with the defense discretionary spending cap for FY2024 established in the Fiscal Responsibility Act (FRA; P.L. 118-5).¹⁵

Table 1 shows requested, proposed, and authorized amounts in the FY2024 NDAA for DOD-military activities (including by major appropriation title), atomic energy defense programs, and certain defense-related activities.

House-passed NDAA

H.R. 2670 would have authorized $874.2 billion—the level of funding the President's budget requested for activities within the scope of the legislation.¹⁶ The bill would have authorized more funding than requested for DOD; less funding than requested for atomic energy defense programs; and more funding than requested for certain other defense-related activities.

During debate of H.R. 2670 in the HASC, Representative Rob Wittman, Chair of the Tactical Air and Land Forces Subcommittee, said he supported an effort by Representative Mike Rogers, Chair of the HASC, to align funding authorized by the legislation to the spending cap in the debt-limit deal negotiated in part by Representative Kevin McCarthy, former Speaker of the House.¹⁷ Wittman said, "The overall debt agreement enacted earlier this year, and the associated appropriations allocations, are the right medicine to our rampant government spending. So, as I begin our debate today, I support Chairman Rogers' defense top line proposal, and Speaker McCarthy's defense approach, to make sure that we rapidly access every programmatic efficiency available."¹⁸ Representative Barbara Lee proposed an amendment that would have reduced the amount authorized by the bill by $100 billion, excluding accounts related to the Defense Health Program, military personnel, and pay and benefits.¹⁹ In a statement, Representative Lee described the amendment, which was not considered for debate, as an effort to "rein in Pentagon spending."²⁰

Senate-passed NDAA

S. 2226 would have authorized $876.8 billion—approximately the level the President's budget requested for activities within the scope of the legislation, after adjusting for a difference in the requested amount for the Air Force, Operation and Maintenance account.²¹ The legislation would have authorized more funding than requested for the DOD and less funding than requested for atomic energy defense programs, including for the Uranium Enrichment Decontamination and Decommissioning Fund. The committee report stated, "The committee recommends an overall discretionary authorization of $886.3 billion in fiscal year 2024"²²—the level of the defense discretionary spending cap for FY2024 in P.L. 118-5.²³

During debate of the bill in a closed session, SASC voted 12-13 opposing an amendment to "raise the topline for implementation of the National Defense Strategy and for other purposes."²⁴ Senator Roger Wicker, Ranking Member of SASC, reportedly filed the motion to increase funding authorized in the legislation by $25 billion.²⁵ On July 19, in remarks on the Senate floor, Senator Wicker said, "Ideally, we would have an annual 3% to 5% boost to our topline above inflation."²⁶ Section 1004 of the proposed bill included a Sense of the Senate provision on the need for emergency supplemental funding in FY2024.²⁷ The section stated, in part, "there are growing national security concerns that require additional funds beyond the revised security spending limit, to include continued support to the Ukrainian armed forces, additional munitions production, additional large surface combatants, shipbuilding industrial base modernization investments, submarine industrial base and supply chain management, additional production of wheeled and tracked combat vehicles, and emergent capabilities and exercises in the United States Indo-Pacific Command."²⁸ Senator Elizabeth Warren, who opposed reporting the legislation to the Senate,²⁹ previously described the FY2024 DOD budget request as "massive" and expressed concern that the department's unfunded priorities lists "distort our budget process."³⁰

In Statements of Administration Policy on H.R. 2670 and S. 2223, the Biden Administration pledged to work with Congress to set "appropriate and responsible levels of defense and nondefense spending to support the security of the Nation consistent with the Fiscal Responsibility Act."³¹

Enacted NDAA

The enacted FY2024 NDAA authorized $874.2 billion, as requested.³² While the overall level of funding authorized in the FY2024 NDAA matched the President's request, amounts authorized for certain titles in the legislation differed from the request. For DOD, the legislation authorized a total of $210.5 million more funding than the President requested. In terms of major DOD titles, the legislation authorized $1.5 billion more than requested for military construction (MILCON); $1.2 billion more than requested for procurement; $965.1 million more than requested for research, development, test, and evaluation (RDT&E); $2.1 billion less than requested for military personnel (MILPERS); $1.2 billion less than requested for operation and maintenance (O&M); and $78.2 million less than requested for other authorizations. For other agencies, the legislation authorized $60 million more than requested for certain defense-related activities; and $270.5 million less than requested for atomic energy defense activities. See Figure 1.

Figure 1. Congressional Changes to President's Requested Funding Authorizations in Proposed and Enacted Versions of the FY2024 NDAA, by Selected Titles (in billions of dollars of discretionary budget authority)

Source: CRS analysis of U.S. Congress, House Committee on Armed Services, James M. Inhofe National Defense Authorization Act for Fiscal Year 2023, Legislative Text and Joint Explanatory Statement to Accompany H.R. 7776, P.L. 117-263, Book 2 of 2, committee print, 118th Congress, 1st sess., January 2023, 50-665, pp. 2168-2173; H.Rept. 118-125 accompanying H.R. 2670, pp. 421-426; S.Rept. 118-58 accompanying S. 2226, pp. 400-403; and U.S. Congress, Conference Committee, National Defense Authorization Act for Fiscal Year 2024, conference report to accompany H.R. 2670, 118th Cong., 1st sess., H.Rept. 118-301, December 6, 2023, pp. 1390-1395. Notes: Amounts in billions of dollars of discretionary budget authority.

In terms of line-item level adjustments to DOD MILCON projects, the legislation authorized some of the biggest funding increases for natural disaster recovery efforts at Tyndall Air Force Base, FL; an unspecified pilot program in the U.S. Indo-Pacific Command (INDO-PACOM) area of responsibility; and a water reclamation facility compliance upgrade at Marine Corps Base, HI.³³

With respect to DOD procurement programs, the legislation authorized some of the biggest funding increases for ships (e.g., LPD-33 amphibious assault ship and DDG-51 destroyer advance procurement [AP]), aircraft (e.g., E-2D electronic attack aircraft, P-8A maritime surveillance aircraft, CH-47 cargo helicopter, V-22 tilt-rotor aircraft), and weapons and combat vehicles (e.g., M-1 Abrams tank upgrades, M-109 Paladin howitzer [cannon], Stryker armored vehicle upgrades).³⁴

Regarding line-item level adjustments to DOD RDT&E programs, projects, and activities, the legislation authorized some of the biggest funding increases—other than realignments of requested funding to separate line items—for Space Force classified programs; the Adaptive Engine Transition Program (AETP) to develop advanced engine prototypes for fighter aircraft; hypersonic defense technology (i.e., glide phase interceptor identified as a priority by the Missile Defense Agency); Precision Strike Weapons Development Program to develop a Nuclear-Armed Sea-Launched Cruise Missile (SLCM-N); and a Joint All Domain Command and Control (JADC2) effort to develop a Joint Fires Network.³⁵

The legislation authorized less funding than requested for DOD MILPERS appropriations largely due to "underexecution," or lower spending than projected, related to end-strengths, the authorized personnel levels of branches of the military.³⁶ Certain military services have struggled to meet recruiting goals.³⁷

In terms of line-item level adjustments to DOD O&M activities, the legislation authorized some of the biggest funding decreases for "undistributed" line items in Navy, Air Force, and Army operation and maintenance appropriations, due to foreign currency fluctuations and unobligated balances.³⁸

With respect to line-item level adjustments to DOD other authorizations, the legislation authorized some of the biggest funding decreases for certain Defense Health Program activities (e.g., in-house care, private care).³⁹

Regarding line-item level adjustments to other agency authorizations, the legislation authorized the biggest funding increase for the Department of Transportation Maritime Administration's Tanker Security Program, which provides DOD with access to a fleet of commercial vessels to supply the armed forces with fuel during conflicts or emergencies.⁴⁰

In terms of line-item level adjustments to atomic energy defense activities, the legislation authorized the biggest funding decrease for defense uranium enrichment decontamination and decommissioning.⁴¹

Summary of Legislative Activity⁴²

By law, the President is to send a federal budget request to Congress by the first Monday in February.⁴³ In practice, the request is sometimes delayed. On March 9, 2023, President Biden submitted initial documentation supporting the FY2024 budget request, including proposed funding for the national defense-related activities.⁴⁴

Table 2 provides a summary of major legislative activity on the FY2024 NDAA, including key legislative documentation produced as part of the process. For a detailed description of congressional actions on the legislation, see Appendix B.

Appendix A. Selected Historical Data

This section of the Appendix provides selected historical data on the NDAA, including a table comparing requested and authorized funding levels over the past decade, and a figure showing the days between the start of the fiscal year and enactment of the legislation.

Requested and Authorized Funding in the NDAA, FY2014-FY2024

Table A-1 shows the change from requested to authorized funding in the NDAA over the past decade.

Days Between Start of Fiscal Year and Enactment of Annual Defense Authorization, FY1977-FY2024

Figure A-1 shows the number of days between the start of the fiscal year and enactment of the annual defense authorization act since FY1977, when the federal government transitioned to a fiscal year beginning October 1, 1976.

Figure A-1. Days between Start of Fiscal Year and Enactment of Annual Defense Authorization Acts, FY1977-FY2024 (in days)

Source: CRS analysis of dates of enactment of public law from CRS Report 98-756, Defense Authorization and Appropriations Bills: FY1961-FY2021; P.L. 117-81; P.L. 117-263; and P.L. 118-31. Notes: Positive values indicate number of days between start of the fiscal year and enactment of annual defense authorization acts. The figure shows that since FY1977 annual defense authorization legislation has been enacted, on average, 43.5 days after the beginning of the fiscal year (i.e., early November). Since FY2020, the legislation has been enacted, on average, 85 days after the beginning of the fiscal year (i.e., late December). Negative values indicate number of days between enactment of annual defense authorization acts and start of fiscal year. Annual defense authorization legislation for the fiscal years 1979, 1989, 1996, 2008, 2016, and 2021 was enacted over a presidential veto.

Appendix B. Detailed Legislative Activity

This section of the Appendix provides a detailed description of congressional actions on the FY2024 NDAA.

House-passed NDAA

In the House, on June 12, 2023, leaders of the seven subcommittees of the House Armed Services Committee (HASC) released draft legislative proposals (known as marks) for matters in the FY2024 NDAA under their respective jurisdictions.⁴⁵ On the same day, Representative Mike Rogers, Chair of HASC, released his draft legislative proposal (i.e., Chairman's mark) for portions of the bill not in the subcommittee marks.⁴⁶ On June 13-14, the HASC subcommittees considered and reported their marks to the full committee.⁴⁷ On June 21, the HASC considered amendments to the subcommittee marks and Chairman's mark before voting 58-1 to order the legislation reported to the House with an amendment in the nature of a substitute, reflecting the product of the committee markup.⁴⁸ On June 30, the committee reported the bill, H.R. 2670, and filed its accompanying report, H.Rept. 118-125.⁴⁹ On July 11-12, the House Rules Committee met to report an initial structured rule, H.Res. 582, for the House to consider H.R. 2670.⁵⁰ On July 13, the committee reported a second structured rule, H.Res. 583.⁵¹ On July 12-14, the House considered amendments to the legislation.⁵² On July 14, the House passed the measure, as amended, by a vote of 219-210.⁵³

Senate-passed NDAA

In the Senate, on June 20-21, 2023, the seven subcommittees of the Senate Armed Services Committee (SASC) marked up draft legislative proposals with recommendations for matters in the FY2024 NDAA under their respective jurisdictions.⁵⁴ One of the markups was held in an open session (Subcommittee on Personnel), and six were held in closed sessions. On June 21-22, the full committee considered the legislation in closed sessions. On June 23, Senators Jack Reed and Roger Wicker, Chair and Ranking Member, respectively, of SASC, announced the committee voted 24-1 to order reported an original bill reflecting the product of the committee markup.⁵⁵ On July 11, S. 2226 was reported to the Senate; on July 12, the accompanying report, S.Rept. 118-58, was filed.⁵⁶ On July 19, the Senate began considering S. 2226, to which Senator Chuck Schumer, the Senate Majority Leader, then offered (for Senator Reed) a complete substitute amendment (S.Amdt. 935) based on the text of S. 2226 and additional provisions. Amendments to the substitute were considered and adopted.⁵⁷ On July 27, the Senate passed the measure, as amended, by a vote of 86-11.⁵⁸ Pursuant to a unanimous consent agreement, immediately after passage of the bill, the Senate took up H.R. 2670 and agreed to an amendment consisting of the text of the just-passed S. 2226, then passed H.R. 2670 with that amendment.⁵⁹

Enacted NDAA

Unlike for the FY2022 and FY2023 bills,⁶⁰ the House and Senate agreed to convene a conference committee to reconcile the two versions of the FY2024 NDAA.⁶¹ On December 6, 2023, the conferees filed a conference report, H.Rept. 118-301, containing the text of the negotiated bill and the accompanying joint explanatory statement of the committee of conference. On December 12, the Senate voted 85-15 to invoke cloture on the conference report. On December 13, the Senate voted 87-13 to agree to the conference report. On December 14, the House considered the conference report under its suspension of the rules procedures and voted 310-118 to agree to the conference report, allowing the measure to be enrolled for presentation to the President. On December 22, President Biden signed the legislation into law.

Appendix C. Related CRS Products

Military Personnel

CRS Insight IN12196, FY2024 NDAA: Basic Needs Allowance and Military Food Insecurity

CRS Insight IN12202, FY2024 NDAA: Military Child Care Programs

CRS Insight IN12205, FY2024 NDAA: Junior Reserve Officers' Training Corps (JROTC) Matters, by Kristy N. Kamarck

CRS Insight IN12217, FY2024 NDAA: Military Spouse Employment Matters.

Defense Health Care

CRS Insight IN12236, FY2024 NDAA: Reproductive Health Care Provisions

CRS Insight IN12203, FY2024 NDAA: TRICARE Coverage of Gender-Affirming Care

CRS Insight IN12215, FY2024 NDAA: TRICARE for Reservists

CRS Insight IN12268, FY2024 NDAA: Military Mental Health Workforce Provisions

CRS Insight IN12263, FY2024 NDAA: Military Mental Health Strategy Development and Program Assessment Provisions

CRS Insight IN12242, FY2024 NDAA: Military Mental Health Care and Research Provisions.

Defense Infrastructure

CRS Insight IN12229, FY2024 NDAA: Military Construction and Housing Authorizations

CRS Insight IN12273, FY2024 NDAA: U.S. Military Posture in the Indo-Pacific.

Defense Management and Acquisition

CRS Insight IN12221, FY2024 NDAA: Defense Industrial Base Policy

CRS Insight IN12225, FY2024 NDAA: Department of Defense Acquisition Policy

CRS Insight IN12254, FY2024 NDAA: Department of Defense Office of Cost Assessment and Program Evaluation (CAPE)

Security Cooperation

CRS Insight IN12256, FY2024 NDAA: Security Cooperation