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What Is an Invitation to Bid in Construction?

By Wyatt Cooper · Published · 4 min read

Key takeaways

  • An invitation to bid (ITB) asks contractors for a firm price on work the documents already define, by a stated date and time.
  • Federal rules call it an invitation for bids, and the responses to it are bids; a request for proposals gets proposals, and a request for quotations gets quotations.
  • A general contractor sends one ITB per trade package, so each subcontractor prices only its own scope.

An invitation to bid (ITB) is the request an owner or general contractor sends to contractors asking for a price on defined work by a set deadline. It names the project and the scope, lists the drawings, specifications and addenda to price, and gives the due date, any bond and insurance requirements, and the bid form to return.

What an invitation to bid contains

An ITB carries everything a bidder needs to price the same work as every other bidder. Federal sealed bidding puts it plainly: invitations "must describe the requirements of the Government clearly, accurately, and completely," and the invitation "includes all documents (whether attached or incorporated by reference) furnished prospective bidders for the purpose of bidding" (FAR 14.101). On private work, the owner's instructions to bidders do the same job; AIA publishes one as A701, Instructions to Bidders (AIA).

Invitation to bid: electrical

Project
Larkspur Clinic, tenant improvement
Package
26 Electrical
Documents
Drawings E0.1–E4.2; spec Divisions 26 and 28; Addendum 1
Scope
Written scope with 14 numbered items
Alternates
Alt 1: LED fixture upgrade in corridors
Questions due
March 3, 2:00 p.m.
Bids due
March 10, 2:00 p.m.
Requirements
Bid on the attached form; insurance per the subcontract; 100% performance and payment bond as a separate add
A general contractor's invitation to bid for one trade (fictional)

How to write and send one, step by step, is in how to send an invitation to bid. The package it goes out with is a bid package, and its heart is the scope of work.

Invitation to bid vs. RFP vs. RFQ

Three ways to ask for a price, as federal rules name them (FAR 2.101)
RequestWhat comes backHow the award is decided
Invitation to bid (invitation for bids)BidsPrice, on documents already complete
Request for proposals (RFP)ProposalsPrice and other factors, often with negotiation
Request for quotations (RFQ)Quotations, which are not offersUsually small purchases

In FAR 2.101, "solicitations under sealed bid procedures are called 'invitations for bids,'" and the responses are offers called bids. On private jobs the words blur, but the difference holds: an ITB asks for a price on defined work; an RFP asks how a contractor would do the work and for how much.

How it works in Conflo

In Conflo's trade bids, each package has its scope, scope items, alternates and a due date and time. You invite subcontractors from your directory, see each invitation move from invited to viewed, bidding, declined or submitted, and answer questions once for every bidder.

An electrical bid invitation as the subcontractor sees it in Conflo: who it is from and when bids are due, a trade addendum to acknowledge before bidding, the scope of work with its scope items and the alternates to price, and the questions and answers shared with every bidder.
An invitation to bid as the subcontractor sees it in Conflo: who it is from, when bids are due, the scope items, alternates and shared questions.

The bottom line

An invitation to bid is a request for a firm price on defined work, with everything the bidder needs attached and a deadline to meet.

Send one per trade, with the same documents to every bidder, and the bids that come back can be compared.

See how trade bids work

Sources

  1. FAR 2.101, Definitions (solicitation, offer) — Acquisition.gov, U.S. General Services Administration. Read October 22, 2026.
  2. FAR 14.101, Elements of sealed bidding — Acquisition.gov, U.S. General Services Administration. Read October 22, 2026.
  3. List of document synopses by family (A701, Instructions to Bidders) — AIA Contract Documents. Read October 22, 2026.

Questions

Is an invitation to bid the same as an invitation for bids?

Yes. Federal and many public agencies say invitation for bids (IFB); contractors often say invitation to bid (ITB) or bid invite. All mean a request for sealed or firm prices on defined work.

Does an invitation to bid bind the GC to award?

Usually not. A private invitation normally reserves the right to reject any bid. Public sealed bidding is stricter: the award goes to the responsible bidder whose conforming bid is most advantageous on price.

What should a subcontractor check in an ITB first?

The due date and time, the documents and addenda listed, the scope items, and any bond and insurance requirements. Price exactly what is listed, and ask before the questions deadline about anything unclear.

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