Every federal request for proposals issued under negotiated procurement follows a fixed blueprint, and two of its lettered sections decide who wins. Section L tells you how to build your proposal; Section M tells you how the government will grade it. The rules that govern both sit in FAR 15.304 and the surrounding subpart. This guide explains what each section must contain, what an agency is allowed to keep to itself, and where the regulation gives you legal footing to challenge an evaluation that departs from the criteria it published.
Background
The Uniform Contract Format organizes every negotiated solicitation into lettered sections so offerors can find the same information in the same place across agencies. Under FAR 15.204-5, Part IV is titled "Representations and Instructions." Within it, Section K covers representations and certifications, Section L is "Instructions, conditions, and notices to offerors or respondents," and Section M is "Evaluation factors for award." The order tracks the sequence of a bid: K is what you certify, L is how you assemble and submit your response, and M is the yardstick the source-selection team applies afterward.
Section L is procedural. It sets page limits, volume structure, formatting, the number of copies, submission deadlines, and any technical or oral-presentation instructions. Miss an instruction here and your proposal can be found noncompliant before anyone reads its substance. Section M is substantive. It names the evaluation factors and subfactors, states their relative importance, and describes how technical merit will be weighed against cost or price. Read the two together: every claim you make in response to Section L should map to something the agency told you it would score in Section M.
Key Details
FAR 15.304(d) sets the disclosure floor. "All factors and significant subfactors that will affect contract award and their relative importance shall be stated clearly in the solicitation." The same provision draws a firm line at method: "The rating method need not be disclosed in the solicitation." An agency must tell you what it will evaluate and how much each factor counts, but it is not obligated to publish the adjectival scale, color code, or point scheme its evaluators use behind the curtain.
FAR 15.304(e) governs the price relationship. Unless an exception applies, the solicitation must state whether the non-cost factors, combined, are "significantly more important than cost or price," "approximately equal to cost or price," or "significantly less important than cost or price." That single sentence tells you where to spend your proposal budget. A narrow exception at 15.304(c)(1)(ii)(A) lets the Department of Defense, NASA, and the Coast Guard drop price as an evaluation factor on certain multiple-award contracts, so on those vehicles the trade-off language may look different.
The binding force of Section M comes from FAR 15.305(a): "An agency shall evaluate competitive proposals and then assess their relative qualities solely on the factors and subfactors specified in the solicitation." The word "solely" is the hook. Evaluators cannot credit a strength the solicitation never advertised, and they cannot penalize you against an unstated standard. Two subsections add texture. Under 15.305(a)(1), a cost-reimbursement evaluation "shall include a cost realism analysis," meaning a lowball estimate can be adjusted upward to what the government judges the work will actually cost. Under 15.305(a)(2), past performance is "one indicator of an offeror's ability to perform," and the agency must weigh currency, relevance, source, and trends rather than treating a stale or off-scope reference as decisive.
When an evaluation strays from the published factors, the forum for challenge is the Government Accountability Office. GAO defines a bid protest as "a challenge to the award or proposed award of a contract for the procurement of goods and services or a challenge to the terms of a solicitation for such a contract." Its procedures are set out in the Bid Protest Regulations at 4 C.F.R. §§ 21.0–21.14, and its plain-language explainer, "Bid Protests at GAO: A Descriptive Guide" (Tenth Edition, 2018), walks through timeliness and standing. The pairing matters: FAR 15.305(a) creates the standard, and GAO is where you enforce it if evaluators score you on something Section M never mentioned.
What It Means for Contractors
A practical read starts with the amendments. Solicitations change, and an amendment to Section L or Section M can shift a page limit, add a subfactor, or reorder the importance of factors midstream; the version that governs your bid is the final amended text, not the base issuance. Track every change and re-run your compliance matrix against it. Where Section M references past performance or a specific technical factor, cross-check the corresponding Section L instruction to confirm you are submitting the exact evidence the evaluation asks for, in the format and volume the instructions require, so the two sections stay locked together throughout your response.
Read Section M before you write a word of your technical volume. The factor order and the importance statement under 15.304(e) tell you where the points are; a proposal weighted toward a factor the agency called "significantly less important than cost or price" wastes effort you should have spent on price or on the dominant technical factor. Build a compliance matrix that maps every Section L instruction and every Section M subfactor to a specific location in your response, so nothing the agency will score goes unaddressed and nothing it will not score bloats your page count.
Do not expect the rating method. Because 15.304(d) lets the agency withhold its scoring mechanics, your job is to write to the factors as stated, in the language of the solicitation, and to make each strength unmistakable rather than guessing at a hidden point curve. On cost-reimbursement work, price your proposal to survive the cost realism analysis required by 15.305(a)(1): an unrealistically low estimate can be probed and adjusted, erasing the advantage you thought it bought. On past performance, choose references that are current, relevant, and close in scope, because 15.305(a)(2) directs evaluators to weigh exactly those attributes.
Finally, treat Section M as a contract about the contest itself. If a debriefing reveals you were downgraded on a consideration that never appeared in the evaluation factors, 15.305(a)'s "solely" language and the GAO protest forum give you a concrete, regulation-backed basis to object within the timeliness windows in 4 C.F.R. Part 21. The discipline that wins the award and the discipline that supports a protest are the same: hold both the agency and yourself to what the solicitation actually said.
