What is the main difference between an RFP and an RFB?

An RFB (Request for Bid) is price-driven — the lowest responsive, responsible bidder wins. An RFP (Request for Proposal) is value-driven — the buyer evaluates technical approach, past performance, and price together.

When do governments use RFBs vs RFPs?

RFBs are used when requirements are well-defined and commoditized (paving, supplies, construction to spec). RFPs are used when the buyer needs the contractor's expertise to shape the solution (IT services, consulting, complex systems).

Can you negotiate after submitting?

RFBs are typically firm — no negotiation, the award goes to the lowest qualifying bid. RFPs allow for clarifications, best-and-final offers (BAFO), and negotiation before award.

RFP vs RFB: What's the Difference?

Two of the most common solicitation formats in government contracting — and one of the most expensive mistakes small businesses make is responding to them the same way. Here's how RFPs and RFBs actually differ, and how to know which one you're looking at.

Quick comparison

Aspect	RFB (Request for Bid)	RFP (Request for Proposal)
Primary driver	Lowest price	Best value (technical + price)
Scope	Fully defined by buyer	Buyer states the problem; you propose the solution
Evaluation	Pass/fail responsiveness, then low bid wins	Weighted scoring across multiple criteria
Negotiation	None — firm bid	Clarifications and BAFO common
Typical use	Construction to spec, supplies, paving, commodities	IT services, consulting, R&D, complex systems
Response effort	Low — fill in pricing forms, attach bonds/certs	High — technical narrative, past performance, staffing

When you'll see an RFB

An RFB (sometimes called an IFB — Invitation for Bid) shows up when the buyer already knows exactly what they want. The plans are drawn, the spec is written, the quantities are listed. Their job is to find the cheapest responsible vendor who can deliver to that spec.

Your job in an RFB is precision: meet every requirement, attach every required certification and bond, price it sharply, and submit on time. There is no creativity points — being "the most innovative bidder" doesn't matter if you're not the lowest responsive bid.

When you'll see an RFP

An RFP appears when the buyer knows the outcome they want but not exactly how to get there. They want vendors to bring expertise — a technical approach, a staffing plan, a project methodology, references that prove you've done it before.

Evaluation is weighted. A typical RFP might score 40% technical approach, 25% past performance, 20% key personnel, and 15% price. The lowest price loses if the technical proposal is weak. The highest price wins if the value is clearly superior.

Other formats you'll run into

RFQ (Request for Quote): Lightweight pricing request, usually for commercial items under a simplified acquisition threshold. Often a short turnaround, minimal paperwork.
RFI (Request for Information): Market research, not a buying action. Respond to shape the eventual RFP/RFB — but don't bill it as a pursuit.
Sources Sought: Pre-solicitation notice to identify qualified small businesses. Critical for influencing whether the final solicitation gets set aside.

How to decide if you should bid

The qualifier is different for each format:

RFB: Can you deliver to the spec profitably at a competitive price? If your cost structure is high, walk away early.
RFP: Do you have the past performance, capability, and staff to score well on the evaluation criteria? Price alone won't save a thin technical proposal.

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