How US construction bidding works: ITB vs RFP vs IFB vs CMAR
US owners buy construction through a few solicitation types. An ITB or IFB asks for sealed bids and awards to the lowest responsive, responsible bidder. An RFP weighs price against qualifications and approach, so the lowest price can lose. CMAR selects a construction manager early, largely on qualifications, who later commits to a guaranteed maximum price.
What is the difference between an ITB, IFB, RFP and CMAR?
The name on the cover tells you how the owner will pick a winner, and so what to read first.
| Solicitation | How the award is made | Typical use | Read first |
|---|---|---|---|
| ITB (invitation to bid) | Sealed price; lowest responsive, responsible bidder | Public design-bid-build; GC invitations to subs | Bid form, instructions to bidders, addenda |
| IFB (invitation for bids) | Federal sealed bidding: public opening, award on price and price-related factors (FAR 14.101) | Federal construction with complete documents | Bid schedule, FAR clause list, wage determination |
| RFP (request for proposals) | Best value: price traded off against stated non-price factors (FAR 15.101-1); Texas also uses competitive sealed proposals | Federal negotiated work, design-build, complex public work | Evaluation factors and their weights |
| CMAR (construction manager at risk) | CM selected through an RFP or RFQ with weighted criteria; contracted price may be a GMP | Public buildings, schools, healthcare | Selection criteria, fee and general conditions structure |
In Texas, Government Code Chapter 2269 sets these methods for public owners. For CMAR, Subchapter F requires the CM to publicly advertise for trade bids or proposals on all major elements of the work (2269.255). "Solicitation" is the umbrella word, used on SAM.gov for all of them.
What is in a construction bid package?
| Document | What it does | Common standard |
|---|---|---|
| Instructions to bidders | Deadline, bid security, required forms. Missing one can make the bid non-responsive. | AIA A701, owner template |
| Bid form | Exactly what to price: base bid, alternates, unit prices, allowances | Owner template |
| Agreement and general conditions | Risk allocation: time, payment, indemnity, claims, termination | AIA A101/A201, ConsensusDocs 200, EJCDC |
| Supplementary conditions | Project-specific edits to the general conditions, where risk is usually shifted | Project-specific |
| Specifications | Products, quality, execution, by CSI MasterFormat division | CSI MasterFormat |
| Drawings | Geometry and connections; read against the specs | A/E set |
| Bonds, insurance and compliance forms | Bid security, performance and payment bonds, wage determinations, participation forms | FAR 52.228 series, state statutes |
| Addenda | Changes issued before bid day; they control over earlier documents | Owner-issued |
What makes a bid non-responsive?
On federal sealed bids, a bid "must comply in all material respects with the invitation for bids" (FAR 14.301). State and local rules are similar. The usual causes:
- Late, or delivered to the wrong place or portal.
- Missing or wrong bid security (bid bond form, amount, surety).
- Addenda not acknowledged.
- Bid form altered, qualified or incomplete; alternates or unit prices left blank.
- Required forms missing: wage, participation, affidavits, signatures.
Which clauses should you find first in any package?
These are the terms precon teams commonly check before spending pricing time. Each has its own guide.
| Finding | Where it lives | Why it matters |
|---|---|---|
| Liquidated damages with no cap | Agreement (AIA A101 4.5) and supplementary conditions | Schedule slip turns into uncapped cost. LD guide |
| Broad-form indemnity | Edits to A201 3.18 or ConsensusDocs 200 10.1 | You cover losses you did not cause. Indemnity guide |
| Pay-if-paid for subs | Subcontract form in the package | Shifts owner nonpayment risk down the chain |
| Retainage (retention) terms | Agreement and supplementary conditions | Cash held to the end of the job |
| Public compliance terms | FAR 52 clause list, wage determinations, participation goals | Price and responsiveness. Compliance guide |
Clara, BAU AI's bids and RFPs agent, scans 1,000+ bid portals for the bids that fit, reads the whole package, flags these risks with page cites, and drafts your Go/No-Go. See Clara at work for one package read end to end.
Guides in this series
Construction bid package review checklist
What to read, in what order, before you price.
ScorecardGo/No-Go bid decision
A weighted bid/no-bid checklist and how to record the call.
Public workPrevailing wage, DBE goals and FAR clauses
What public bids require, with the DBE status as of October 2026.
Frequently asked questions
Is an ITB the same as an IFB?
In practice, yes: both ask for sealed prices against complete documents. IFB is the federal term under FAR Part 14 sealed bidding; ITB is common on state, local and private work, including GC invitations to subcontractors.
When does the lowest bid lose?
On an RFP or other best-value selection, the owner can pick a higher price if its stated non-price factors justify it. On a sealed bid, the lowest bid loses if it is non-responsive or the bidder is not responsible.
What is a bid bond?
A surety's guarantee that the bidder will sign the contract and provide the required bonds if it wins. The amount is set in the instructions to bidders; on federal work the contracting officer sets it under FAR 28.101-2.
What happens if you miss an addendum?
Addenda control over earlier documents, so you may price the wrong scope, and a missing acknowledgment can make the bid non-responsive. Check for new addenda the day before bid day.
How does CMAR pricing work?
The construction manager is selected early, largely on qualifications and fees, then provides a contracted price that may be a guaranteed maximum price. In Texas public CMAR, the CM must publicly solicit bids or proposals from trade contractors for the major elements of the work.