FAR 15.001—Definitions.
Plain-English Summary
FAR 15.001 provides the core definitions used in negotiated procurement under FAR part 15, and it is especially important because these terms drive how proposals are evaluated, discussed, corrected, and ultimately selected for award. This section defines four key concepts: deficiency, proposal modification, proposal revision, and weakness, including the more serious category of significant weakness. In practice, these definitions control how evaluators describe proposal flaws, how contracting officers distinguish between changes made before closing versus after closing, and when discussions or negotiations may lead to a revised proposal. The definitions also matter because they affect source selection documentation, competitive range decisions, and the risk assessment of whether a proposal can successfully perform the contract. For contractors, these terms shape how they should respond to amendments, correct mistakes, and manage post-closing negotiations without crossing procedural lines. For contracting officers and evaluators, the definitions provide the vocabulary and standards needed to assess proposal quality consistently and fairly.
Key Rules
Deficiency means material failure
A deficiency exists when a proposal materially fails to meet a Government requirement, or when multiple significant weaknesses together raise the risk of unsuccessful performance to an unacceptable level. This is a serious evaluation finding, not just a minor flaw, and it signals that the proposal may be unacceptable unless corrected or clarified through the procurement process.
Weakness is a proposal flaw
A weakness is any flaw in the proposal that increases the risk of unsuccessful contract performance. Weaknesses are less severe than deficiencies, but they still matter because they can affect the proposal’s technical merit, confidence in performance, and overall evaluation standing.
Significant weakness raises risk more
A significant weakness is a flaw that appreciably increases the risk of unsuccessful contract performance. It is more serious than an ordinary weakness and may contribute to a deficiency when several significant weaknesses together create an unacceptable risk level.
Proposal modification before closing
A proposal modification is a change made before the solicitation closing date and time, or in response to an amendment, or to correct a mistake at any time before award. This definition covers pre-closing changes and certain corrections made before award, and it helps distinguish permissible proposal updates from post-closing revisions.
Proposal revision after closing
A proposal revision is a change made after the solicitation closing date, at the request of or as allowed by the contracting officer, as a result of negotiations. This term is tied to negotiated procurements and reflects changes made during discussions or negotiations after proposals have been submitted.
Responsibilities
Contracting Officer
Use these definitions to determine whether proposal flaws are weaknesses, significant weaknesses, or deficiencies; decide when a proposal change is a modification versus a revision; and ensure post-closing changes occur only when requested or permitted during negotiations. The contracting officer must also document evaluation findings consistently and use the terms correctly in discussions, competitive range decisions, and source selection records.
Evaluators / Source Selection Team
Identify and record proposal flaws using the FAR definitions, distinguishing ordinary weaknesses from significant weaknesses and deficiencies. Evaluators must assess how each flaw affects performance risk and provide clear, supportable rationale for the evaluation record.
Contractor / Offeror
Prepare proposals that meet Government requirements, respond carefully to amendments, and understand when changes are allowed before closing versus after closing. Offerors should correct mistakes and submit modifications timely, and if negotiations occur, they should treat proposal revisions as controlled changes made only as permitted by the contracting officer.
Agency / Source Selection Authority
Rely on the defined terms when reviewing evaluation results and making award decisions, especially where weaknesses or deficiencies affect competitive standing or risk. The agency must ensure consistent application of the definitions across the procurement to support fairness and defensibility.
Practical Implications
These definitions are the language of proposal evaluation, so using them correctly is essential for defensible source selection decisions and clear communication with offerors.
A common pitfall is treating every flaw as a deficiency; in reality, the FAR distinguishes between weaknesses, significant weaknesses, and deficiencies based on severity and performance risk.
Contractors should pay close attention to the timing of changes: before closing, changes are proposal modifications; after closing, changes are proposal revisions only if the contracting officer requests or allows them during negotiations.
Multiple significant weaknesses can combine into a deficiency, so evaluators should assess cumulative risk rather than looking at each flaw in isolation.
Clear documentation matters: evaluators and contracting officers should explain not just what the flaw is, but how it affects the risk of unsuccessful performance.
Official Regulatory Text
As used in this part- Deficiency is a material failure of a proposal to meet a Government requirement or a combination of significant weaknesses in a proposal that increases the risk of unsuccessful contract performance to an unacceptable level. Proposal modification is a change made to a proposal before the solicitation closing date and time, or made in response to an amendment, or made to correct a mistake at any time before award. Proposal revision is a change to a proposal made after the solicitation closing date, at the request of or as allowed by a contracting officer, as the result of negotiations. Weakness means a flaw in the proposal that increases the risk of unsuccessful contract performance. A "significant weakness" in the proposal is a flaw that appreciably increases the risk of unsuccessful contract performance.