Acquisition Category (ACAT): DoD Tiers, MDAPs, and Thresholds

The Department of Defense sorts its major acquisition programs into acquisition categories, known as ACATs, using two cost figures: research and development spending and total procurement spending. A program lands in ACAT I, II, III, or (in the Navy and Marine Corps only) ACAT IV depending on which thresholds it crosses, and that placement determines who signs off on its milestones, how much documentation it produces, and how closely Congress watches it. All thresholds are stated in fiscal year 2020 constant dollars so that inflation alone cannot push a program into a heavier oversight tier.

How the Thresholds Work

Two numbers drive every designation. Research, Development, Test, and Evaluation (RDT&E) costs cover the early lifecycle: design, prototyping, and testing to confirm the technology works. Procurement costs cover manufacturing and fielding the finished system at scale. A program only has to exceed the threshold on one of the two metrics to qualify for a given category.

Because the figures are pegged to FY 2020 purchasing power under DoDI 5000.85, programs that started years apart can be compared on the same footing. A dollar figure in the categorization rules is not the dollar figure on this year’s invoice.

ACAT I: The Largest Programs

A program enters ACAT I when its estimated RDT&E costs exceed $525 million or its total procurement costs exceed $3.065 billion, both in FY 2020 constant dollars.¹ These are the platforms most people picture when they think of defense procurement: next-generation fighters, aircraft carriers, integrated missile defense. Oversight is at its most intensive, with detailed documentation at every phase, frequent senior-leadership reviews, and mandatory reporting to Congress.

ACAT I splits into three sub-tiers according to who holds Milestone Decision Authority (MDA), the official who approves a program’s move from one acquisition phase to the next:

ACAT ID. The Under Secretary of Defense for Acquisition and Sustainment (USD(A&S)), acting as the Defense Acquisition Executive, is the MDA. These are the programs the Pentagon’s top acquisition official oversees directly.²
ACAT IB. The Service Acquisition Executive (SAE) of the relevant military department is the MDA by operation of statute. This designation applies to major defense acquisition programs that reached Milestone A after October 1, 2016.¹
ACAT IC. The USD(A&S) has delegated MDA down to the head of the DoD component, or, on further delegation, to the Component Acquisition Executive (CAE).¹

The IB and IC distinction matters because the source of authority differs. An ACAT IB program’s SAE holds authority by statute, and the USD(A&S) cannot easily reclaim it. An ACAT IC program’s authority exists only because the USD(A&S) delegated it, and that delegation can be reversed. If the USD(A&S) designates a different MDA for what was an ACAT IB program, the Secretary of the relevant military department can request that responsibility revert to the SAE.

ACAT II: Major Systems Below the Top Tier

Programs that qualify as “major systems” but fall short of ACAT I dollar figures sit in ACAT II. The floors are $200 million in RDT&E or $920 million in procurement, again in FY 2020 constant dollars.² The CAE, or an official the CAE designates, serves as MDA.¹

Reporting focuses on technical milestones and budget management within a tighter chain of command. Contractors and program managers still face regular audits, but the documentation load and review frequency are lighter than ACAT I demands. Decisions stay closer to the people who know the program best.

ACAT III

Programs that do not reach the ACAT II thresholds and are not designated as major systems fall into ACAT III. The CAE designates these programs, and the CAE or a designee handles milestone decisions.¹ ACAT III covers the bulk of smaller acquisition efforts, with streamlined reporting so that resources aren’t consumed by heavy bureaucracy on lower-risk work.

ACAT IV: Navy and Marine Corps Only

The Department of the Navy adds a fourth tier for its smallest programs. ACAT IV breaks into two sub-categories:

ACAT IVT. Programs that affect the mission characteristics of ships or aircraft, or that involve combat capability. These still require operational test and evaluation.
ACAT IVM. Programs that do not affect ship or aircraft mission characteristics and do not involve combat capability. These skip independent operational testing but are monitored by the Commander, Operational Test and Evaluation Force.

ACAT IV is unique to the Navy and Marine Corps. The Army and Air Force manage their smallest programs under ACAT III with delegated authority. For all ACAT III and IV programs, decision authority sits at relatively low levels within the military departments, which allows faster turnaround and lower administrative overhead. A Program Executive Officer, for example, can serve as MDA in this range.²

MDAPs Are Defined Separately in Statute

The ACAT I thresholds are not the same as the statutory definition of a “major defense acquisition program.” Under 10 U.S.C. 4201, a program automatically qualifies as an MDAP if it is estimated to require more than $1 billion in RDT&E or more than $4.5 billion in procurement, both in fiscal year 2024 constant dollars.³ The National Defense Authorization Act for Fiscal Year 2024 raised those figures substantially, roughly doubling the prior thresholds when adjusted for inflation. The Secretary of Defense can also designate any program as an MDAP regardless of cost.

The practical result: the DoDI 5000.85 ACAT I thresholds sit well below the statutory MDAP floor. A program that clears $525 million in RDT&E (FY 2020 dollars) will be categorized as ACAT I and managed with full top-tier oversight even if it does not automatically qualify as an MDAP under the current statute. The operational categorization system captures more programs at the highest oversight level than the statute alone would require.

What an ACAT I Designation Actually Triggers

Placement in ACAT I is not just a label. It sets off specific obligations.

Every program on the Major Capability Acquisition pathway, at any ACAT level, must establish an Acquisition Program Baseline (APB): a formal commitment between the program manager and the MDA covering cost, schedule, and performance. Each parameter carries an objective value and a threshold value, and breaching a threshold triggers review. The standard schedule threshold is six months beyond the objective date, and anything more requires written justification.⁴

ACAT I programs also generate Selected Acquisition Reports to Congress. The Secretary of Defense must submit a SAR for each MDAP at the close of every fiscal-year quarter, with the comprehensive annual report due within 30 days after the President’s budget submission and quarterly reports due within 45 days after the end of each fiscal quarter.⁵

Cost growth on an MDAP is policed by the Nunn-McCurdy provisions. A significant breach occurs when unit cost rises at least 15 percent over the current baseline or 30 percent over the original baseline; a critical breach occurs at 25 percent over the current baseline or 50 percent over the original.⁶ A significant breach requires notification to Congress and reassessment. A critical breach carries a statutory presumption of termination unless the Secretary of Defense personally certifies to Congress that the program remains essential, that no cheaper alternative exists, that the new cost estimates are reasonable, that it is a higher priority than the programs whose funding would be cut, and that management is adequate to control costs going forward.⁷

ACATs Apply to One Acquisition Pathway

ACAT designations govern programs on the Major Capability Acquisition pathway, one of six pathways in the DoD’s Adaptive Acquisition Framework. The others cover urgent capability needs, middle-tier rapid prototyping and fielding, software acquisition, defense business systems, and acquisition of services. Programs on those pathways have their own governance and do not receive traditional ACAT designations, though a program on any pathway that exceeds the ACAT I dollar thresholds still draws senior-level attention. Before applying the ACAT thresholds to a program, confirm the pathway.

1
Adaptive Acquisition Framework. Acquisition Categories (ACATs)
2
Department of Defense. DoDI 5000.85 – Major Capability Acquisition
3
Office of the Law Revision Counsel. 10 USC 4201 – Major Defense Acquisition Programs: Definition; Exceptions
4
Adaptive Acquisition Framework. Guidance for Acquisition Program Baselines for Major Capability Acquisition
5
Office of the Law Revision Counsel. 10 US Code 4351 – Selected Acquisition Reports
6
Office of the Law Revision Counsel. 10 USC 4371 – Cost Growth Definitions; Applicability of Reporting Requirements
7
Office of the Law Revision Counsel. 10 USC 4376 – Breach of Critical Cost Growth Threshold: Reassessment of Program; Presumption of Program Termination