You lost the bid. Or you won it and want to know why the runner-up thought they'd win. Either way, a debrief is the one place a contracting officer has to explain the decision to you in something other than a form letter. Most small businesses never ask. That's a mistake, because the request has a clock on it and the clock doesn't wait for you to think it over.
The request has to move fast
Under FAR 15.506(a)(1), if you're a small business (or any offeror on a negotiated procurement), you have to submit your written debrief request within 3 days after you receive notice of the award or exclusion decision. Not 3 business days in every reading of the clause, not "sometime this week." Three days, in writing, to the contracting officer named in the notice.
Miss that window and you're at the CO's discretion. Some will still debrief you. Many won't, and they're not required to. If you take one thing from this post, make it this: put the request in writing the same day you get the notice, not after you've had time to be upset about it.
Once the CO has your request, the debrief itself "should" happen within 5 days, per the same clause. That's a guideline the agency is expected to hit, not an ironclad deadline you can enforce, but it's the number to hold them to.
What the CO has to tell you, and what they don't
FAR 15.506(d) sets the floor. A proper debrief covers the government's evaluation of significant weaknesses or deficiencies in your proposal, your overall cost or price and technical rating, past performance information, the overall ranking of offerors, a summary of the rationale for award, and (for commercial items) the make and model being purchased. You're also entitled to ask whether the source-selection procedures required by the solicitation and applicable regulations were in fact followed.
What you won't get, under FAR 15.506(e), is a side-by-side of your proposal against the winner's. No point-by-point comparison, no other offeror's trade secrets or proprietary technical or financial detail, no names of the references who gave past performance input, and nothing that FOIA would otherwise let the government withhold. A debrief that stays inside those lines isn't the CO stonewalling you. It's the CO following the rule.
Ask questions that fit inside those lines
The debriefs that actually help are the ones where the contractor asks specific, answerable questions instead of "why did we lose." Ask which evaluation factor drove the outcome. Ask whether your proposal had a documented weakness and what it was. Ask whether price or technical merit carried more weight in the tradeoff. Those are all fair game under 15.506(d), and a CO who has to answer a direct question tends to give you more than they'd volunteer unprompted.
Take notes during the debrief itself. It's often verbal, sometimes with slides, and the government isn't obligated to hand you a written record afterward. What you learn becomes the input for your next bid: the weakness you fix, the pricing gap you close, the past performance you go build. None of it guarantees the next award goes differently. It does mean you're bidding with real information instead of a guess.
If you're trying to close that pricing gap with something better than a guess, our price-to-win estimates pull from actual award history in your NAICS codes, not a hunch about what the government usually pays.
A debrief only happens once the government has already worked through the whole evaluation on its own timeline. Here's what actually happens after you submit, the part between hitting submit and hearing anything at all.