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Title 10 MOSA requirements

A section-by-section reading guide to Title 10, chapter 327, subchapter I. The linked U.S. Code text reflects laws through Public Law 119-124 (October 15, 2026).

§ 4401 · Applicability and definitions

10 U.S.C. § 4401 establishes the MOSA design and development requirement and defines the terms used in chapter 327.

  • (a) Applicability. Major defense acquisition programs (MDAPs) receiving Milestone A or B approval after January 1, 2019, must use MOSA to the maximum extent practicable. The subsection separately directs other defense acquisition programs to apply MOSA to the maximum extent practicable.
  • (b) Standards disclosure. The Secretary must make implementation standards for contracts publicly available within one year of enactment of the subsection (December 23, 2024). For a specific contract, a service acquisition executive may request nondisclosure, subject to the Secretary’s approval.
  • (c)(1)(A)–(B) Design and verification. MOSA combines business and technical strategy with modular design. Verify relevant interfaces against widely supported consensus standards where available and suitable, or deliver them under FY2021 NDAA § 804(a)(2)(B). The latter includes machine-readable interface syntax and properties, machine-readable relationships to common standards or repository interfaces, and functional documentation explaining interface semantics.
  • (c)(1)(C)–(D) Lifecycle and data rights. The architecture permits appropriate components and modular systems to be added, removed, or replaced over time. The statute identifies benefits such as cost avoidance, shorter schedules, upgrades, interoperability, and sustainment improvements. The strategy also complies with technical-data rights under §§ 3771–3775.
  • (c)(2)–(6) Core terms. The statute distinguishes the top-level platform, installable major components, physical or logical interface boundaries, independently executable and recombinable modular systems, and the program capability document that specifies requirements.
  • (c)(7)–(9) Incorporated definitions. The statute points to § 4271(a) for program cost and fielding targets, § 4201 for MDAP, and § 101(a) for major weapon system.

§ 4402 · Acquisition decisions

10 U.S.C. § 4402 ties MOSA to MDAP capability development, acquisition planning, solicitation, and Milestone B.

  • (a) Capability document. Characterize which performance requirements are likely to evolve with technology, threats, or interoperability needs. Identify the minimum acceptable initial operating capability for those requirements.
  • (b) Analysis of alternatives. The Director of Cost Assessment and Performance Evaluation must ensure the analysis considers evolutionary acquisition, prototyping, and MOSA.
  • (c) Acquisition strategy. For an MDAP using MOSA, describe the approach under § 4211. Distinguish the platform, internally developed components, and externally developed components planned for integration. Explain anticipated component changes by increment and later additions. Address intellectual property and technical-data deliverables, plus system integration and configuration management for mission and information assurance.
  • (d) Request for proposals. For an MDAP using MOSA, the milestone decision authority must ensure that development or production solicitations describe the approach and the minimum set of major system components required in the design.
  • (e) Milestone B. A written determination precedes approval. For a MOSA program, it covers defined platform-to-component, component-to-component, and platform-to-platform interfaces, consistency with § 4401(a), and arrangements to obtain necessary interface IP rights upon completion of platform development. For a program without MOSA, the determination must find MOSA impracticable.
  • (f) Guidance. The military department secretaries must issue implementation guidance for this section.

§ 4403 · Military department responsibilities

10 U.S.C. § 4403 assigns six duties to each military department secretary.

  • (1) Coordinate. Work with other military departments, defense agencies, industry, standards organizations, and appropriate intelligence community elements on platform interfaces and standards where practicable.
  • (2) Define and deliver. Ensure major system interfaces are designated and defined, and deliver documentation sufficient for third-party component or module integration.
  • (3) Provide expertise. Make engineering and development expertise and resources available for requirements and acquisition planning.
  • (4) Resource lifecycle support. Provide planning, programming, and budgeting resources for MOSA, interfaces, integration, and activities that sustain innovation and interoperability.
  • (5) Train. Provide adequate MOSA training to the requirements and acquisition workforce.
  • (6) Issue guidance. Publish implementing guidance for the section.

Technical data and contract provisions

Section 3771(b)(7) provides for government purpose rights in technical data for a modular system interface developed privately or with mixed funding and used under § 4401, subject to a Secretary determination that negotiating different rights would serve the United States’ best interest.

10 U.S.C. § 3772 specifies contract provisions for technical data, including delivery requirements and provisions addressing use, release, and delivery of covered data. Review the full §§ 3771–3775 range referenced by § 4401(c)(1)(D) when tracing the statutory data-rights requirements.

Related department guidance

Read the Department of War memorandum for the department’s implementation direction.