RFP vs IFB vs RFQ: how to read a government solicitation

Last reviewed Nov 5, 2026 against the official sources listed below.

An IFB (invitation for bids) asks for sealed bids and is awarded to the responsible bidder whose bid meets the requirements at the lowest price, with no negotiation. An RFP (request for proposals) asks for proposals that are evaluated on price and other factors, such as experience and technical approach, and may involve negotiation. An RFQ (request for quotations) is used for smaller, simpler purchases, and a quote is not a binding offer. An RFI (request for information) or sources sought notice is market research only: there is no contract to win yet, but answering it can shape the solicitation that follows. Whatever the type, read the due date and submission instructions first, then the scope of work, then how the agency will pick the winner.

What is an IFB (invitation for bids)?

An IFB is used for sealed bidding, covered by FAR Part 14. The FAR describes sealed bidding as "a method of contracting that employs competitive bids, public opening of bids, and awards." Bids are opened in public at the stated time, and "Bids shall be evaluated without discussions."

Award goes to the responsible bidder whose bid conforms to the invitation and is most advantageous to the government, considering only price and price-related factors. In practice that means: meet every requirement, then be the lowest price. Under FAR 14.404-2, "Any bid that fails to conform to the essential requirements of the invitation for bids shall be rejected," even if it is the cheapest.

Texas cities and counties use the same idea under the name competitive sealed bidding, alongside competitive sealed proposals, for most purchases over $100,000.

What is an RFP (request for proposals)?

An RFP is used for negotiated contracts under FAR Part 15. The agency can weigh price against other factors and select the proposal that is the best value to the government, which is not always the lowest price. The agency may hold discussions with offerors and ask for revised proposals.

Federal RFPs usually follow the Uniform Contract Format in FAR 15.204-1. The sections that matter most when you start:

Section B: supplies or services and prices. What you are pricing, line by line.
Section C: description, specifications or statement of work. What you would actually do.
Section F: deliveries or performance. When and where.
Section L: instructions, conditions and notices to offerors. Page limits, format, what volumes to submit and how.
Section M: evaluation factors for award. How the agency will score proposals and how important each factor is.

Read Sections L and M side by side and build your proposal so each requirement in L is answered in the order M will score it.

What is an RFQ (request for quotations)?

An RFQ is used for simplified acquisitions under FAR Part 13, which covers purchases that do not exceed the simplified acquisition threshold ($350,000 since October 1, 2025), plus some larger commercial purchases. Federal RFQs often use Standard Form 18 (Request for Quotations) or SF 1449 (Solicitation/Contract/Order for Commercial Products and Commercial Services).

The key legal point is in FAR 13.004: "A quotation is not an offer and, consequently, cannot be accepted by the Government to form a binding contract." If the government likes your quote, it issues an order, which is its offer to you, and a contract is established when you accept it. Because simplified acquisitions use simpler procedures, RFQs are a good first target for a small business.

What is an RFI or a sources sought notice?

Both are market research. Under FAR 15.201(e), "RFIs may be used when the Government does not presently intend to award a contract, but wants to obtain price, delivery, other market information, or capabilities for planning purposes. Responses to these notices are not offers." Sources sought notices on SAM.gov work the same way: the agency wants to know who can do the work.

There is nothing to win from an RFI, but a short, specific answer (your capabilities, similar past jobs, size status and certifications) helps the agency decide whether to set the contract aside for small businesses. See our set-asides guide.

What should I read first in any solicitation?

The due date, time and time zone, and how to submit (portal, email or paper). Under the standard federal proposal clause (FAR 52.215-1), a proposal received after the exact time set for receipt is late and is generally not considered.
The scope of work or specifications. Can you do all of it, where and when it needs to be done?
Required forms and certifications: signed solicitation form, representations, bonds, insurance, licenses, and any HUB or small business subcontracting plan.
How the award is decided: lowest price (IFB), best value (RFP Section M) or the simplified terms in an RFQ.
Questions deadline and pre-bid meeting or site visit, if any.
Amendments. Check the posting again before you submit.

What is an amendment and do I have to acknowledge it?

An amendment changes the solicitation: a new due date, answers to questions, revised drawings or quantities. Under FAR 15.206 the contracting officer must amend the solicitation when the government changes its requirements, and IFB amendments are issued on Standard Form 30.

Yes, acknowledge every amendment. The standard IFB provision (FAR 52.214-3) says bidders shall acknowledge receipt of any amendment, for example by signing and returning it or by listing the amendment number and date on the bid form. The standard RFP provision (FAR 52.215-1) requires acknowledgment by the date and time the amendment specifies. LibertyBids sends an update alert when a bid you are tracking gets a new due date or an amendment.

Frequently asked questions

What is the difference between an RFP and an IFB?

An IFB uses sealed bidding: bids are opened publicly, there are no discussions, and award goes to the responsible bidder whose conforming bid is best on price and price-related factors. An RFP is a negotiated procurement: the agency evaluates price and non-price factors, may hold discussions, and picks the best value.

Is a quote in response to an RFQ a binding offer?

No. Under FAR 13.004, a quotation is not an offer and cannot be accepted by the government to form a binding contract. A contract forms when the government issues an order and the supplier accepts it.

Should I respond to a sources sought notice or RFI?

If you want the work, yes. Responses are not offers and no contract is awarded from them, but they are market research that can lead the agency to set the eventual contract aside for small businesses.

What are Section L and Section M in an RFP?

In the federal Uniform Contract Format, Section L holds the instructions, conditions and notices to offerors (how to prepare and submit your proposal) and Section M lists the evaluation factors for award (how proposals are scored and how much each factor counts).

What happens if my proposal is late?

Under FAR 52.215-1, a proposal received at the designated government office after the exact time specified is late and will not be considered except in narrow cases set out in the clause. Submit early.

Official sources

Rules and amounts change. Always confirm with the official source and the solicitation itself before you bid. Spotted something out of date? Email support@libertybids.com.