Federal solicitations come in three main flavors, and the letters on the cover tell you how the government intends to choose. An invitation for bids, a request for proposals and a request for quotations each follow different rules, create different legal relationships and reward different approaches. Confusing them is a common early mistake.
Invitation for bids: sealed bidding
An IFB is used when the agency can describe exactly what it wants, expects more than one bidder and plans to award on price alone. Bids are submitted sealed, opened publicly at a stated time and recorded. The contract goes to the lowest-priced bidder whose bid is responsive, meaning it conforms to the invitation in every material way, and who is found responsible, meaning capable of performing. There are no discussions and no second chances; a bid with a missing signature or an unacknowledged amendment can be rejected outright.
Sealed bidding is governed by FAR Part 14 and is most common in construction and in straightforward supply purchases. If you see an IFB, your proposal is your price, your compliance and your bid bond if one is required.
Request for proposals: negotiated procurement
An RFP is used when the agency wants to weigh more than price: technical approach, past performance, management, key personnel. The rules live in FAR Part 15. Offerors submit written proposals, evaluators score them against the factors in Section M, and the agency may award on initial offers or open discussions with the most competitive firms and request final revisions. The award can go to a higher-priced offeror whose proposal is judged a better value, unless the solicitation says the lowest-priced technically acceptable offer wins.
A proposal submitted in response to an RFP is an offer. If the government accepts it, a contract exists. That is why the terms, assumptions and exceptions in a proposal matter so much.
Request for quotations: an invitation to talk
An RFQ asks for a quotation, and a quotation is not an offer. It is information. The government’s purchase order in response is the offer, and the contract is formed when the contractor accepts it, usually by performing. RFQs are the workhorse of simplified acquisitions, orders under GSA Schedules and orders under existing multiple-award contracts. They tend to be shorter, faster and more informal than RFPs, though a quote still has to meet every stated requirement to be considered.
Why the differences matter in practice
- Flexibility. Under sealed bidding, there is none. Under an RFP, discussions may happen but you should never count on them. Under an RFQ, an agency can often ask follow-up questions informally.
- What wins. IFBs reward the lowest compliant price. RFPs reward the combination the evaluation factors describe. RFQs vary, so read the basis for award carefully.
- Risk of error. Administrative mistakes are fatal in sealed bidding, serious in negotiated procurements and sometimes correctable in RFQs. Treat every submission as if it were sealed.
- Protest grounds. The rules the agency must follow differ by method, which affects what can be challenged.
Reading the cover page
The solicitation number and the first page usually say which method applies. Standard Form 33 commonly fronts an IFB or RFP; Standard Form 1449 fronts a commercial products and services solicitation, which may be an RFQ or an RFP. When in doubt, look for the FAR part the instructions cite. The regulation itself is public at acquisition.gov, and ten minutes with the relevant part will tell you how your offer will be judged.