Invitation to Bid (ITB): What It Is and How It Differs From an RFP
Published on October 8, 2026 in RFP Guides
An invitation to bid (ITB) asks suppliers for a firm price on something the buyer has already specified in full, such as a paving job with finished drawings. Bids usually arrive sealed and are opened at a set time, and the contract usually goes to the lowest-priced bidder that meets every requirement and can do the work. This guide covers when to use an ITB, how it differs from an RFP, RFQ and RFI, and how to respond to one.
What is an invitation to bid?
An ITB is a formal request for prices. The buyer publishes the full requirement, the contract and the bidding rules, and each bidder enters a price on the buyer’s bid form. There are no proposals to score: among bids that meet every requirement, price decides.
The US federal term is invitation for bids (IFB): FAR 2.101 says solicitations under sealed bid procedures are called “invitations for bids”. Some states say invitation to bid, as Virginia’s and Florida’s procurement laws do. In the UK and other countries you’ll also see invitation to tender (ITT).
In construction, ITBs often run at two levels: an owner invites general contractors to bid on a finished design, and each general contractor invites subcontractors to bid on trades such as electrical or concrete work.
When buyers use an ITB
Use an ITB when you can describe the requirement completely, any qualified supplier would deliver the same thing, and price is all that’s left to compare. If you need to compare approaches or products, use an RFP.
FAR 6.401(a) sets a similar federal test, including that the award will be made “on the basis of price and other price-related factors” and that discussions aren’t necessary.
The award normally goes to the lowest responsive and responsible bidder: the cheapest bid that does exactly what the invitation asks, from a bidder able to do the work. FAR 14.101(e) says award goes “to that responsible bidder whose bid, conforming to the invitation for bids, will be most advantageous to the Government, considering only price and the price-related factors included in the invitation.” Price-related factors include transportation costs and taxes (FAR 14.201-8).
ITB vs RFP vs RFQ vs RFI
For the other three in detail, see RFPhub’s RFP vs RFQ vs RFI guide.
| Aspect | RFI | RFP | RFQ | ITB |
|---|---|---|---|---|
| Use it when | You’re still learning the market. | Solutions differ and you’ll judge on more than price. | The requirement is fully specified and suppliers would deliver the same thing. | As for an RFQ, but your rules or the job’s size call for formal, sealed bids. |
| Vendors send | General information. | A detailed proposal with itemized pricing. | Prices, delivery dates and terms. | A sealed bid on your bid form, with any required bid bond. |
| How responses are evaluated | Informally, to build a shortlist. | Scored against weighted criteria set in advance. | Mainly on price and terms, after checking each quote meets the specification. | On price: the lowest responsive bid from a responsible bidder wins. |
| Negotiation | Not applicable. | Yes, with the preferred supplier. | Depends on your rules. | Little or none: the bid price is the price. |
ITB vs RFP comes down to what wins. An RFP weighs price alongside fit and approach, and often leads to demonstrations and negotiation. An ITB is decided on price among bids that meet every requirement, and federal sealed bids are “evaluated without discussions” (FAR 14.101(d)).
An ITB and an RFQ are closer: both price a defined requirement. The ITB is the more formal of the two, with sealed bids, a fixed opening and sometimes a bid bond. Under FAR 2.101, a bid is an offer, while a quotation under simplified acquisition procedures is not.
What goes in an ITB
Every bidder prices the same work, so the package has to be complete. FAR 14.101(a) says federal invitations “must describe the requirements of the Government clearly, accurately, and completely.” Expect these parts:
- Notice: what’s being bought, where to get the documents, and when and where bids are due and opened.
- Instructions to bidders: how to submit and ask questions, how addenda are issued, and the rules on late or withdrawn bids.
- Specifications: drawings and technical specifications, or line items with quantities and delivery dates.
- Bid form: the price schedule every bidder must use, as a lump sum, unit prices or both.
- Qualifications and bonds: licenses, insurance, any bid bond, and the winner’s performance and payment bonds.
- Basis of award and contract terms: how the low bid is worked out, how long bids stay open, and the contract the winner signs.
Sealed bids and public bid openings
Sealed bidding keeps every price secret until all bids are in. Bidders deliver sealed envelopes, or upload to a secure electronic system, before the deadline. The buyer opens them together at the stated time. Public bodies usually do this in public, often reading prices aloud and recording results in a bid tabulation. FAR 14.101 describes sealed bidding as a method that “employs competitive bids, public opening of bids, and awards.”
The apparent low bidder hasn’t won yet: the buyer first checks the bid for mistakes, responsiveness and the bidder’s responsibility. Late bids are generally rejected.
Private ITBs, such as a general contractor’s invitations to subcontractors, generally follow the buyer’s own process, so the ITB should say whether bids are sealed and whether the buyer may negotiate.
Bid bonds and responsiveness
Bid bonds
A bid guarantee, such as a bid bond from a surety company, assures the buyer that the bidder won’t withdraw its bid during the acceptance period and will sign the contract and provide any required bonds (FAR 28.001). Requirements vary by jurisdiction, contract type and value. In federal sealed bidding, failing to meet a bid guarantee requirement “requires rejection of the bid,” apart from listed exceptions (FAR 28.101-4(a)).
Responsiveness and responsibility
Responsiveness is about the bid. FAR 14.301(a) says a bid “must comply in all material respects with the invitation for bids.” Bids can fail this test by adding conditions that change the terms, leaving out a required price or bond, offering something other than what was specified, or not acknowledging a material addendum. Small defects of form can be waived or corrected (FAR 14.405).
Responsibility is about the bidder. Under FAR 9.104-1, the standards include adequate financial resources, the ability to meet the schedule, and satisfactory records of performance and of integrity and business ethics. If the low bidder fails either test, the buyer generally moves to the next-lowest bid.
Check the rules that apply to you
The FAR applies to US federal agency purchasing only. State and local governments set their own rules on when sealed bids are required, what bonds are needed and whether the buyer may negotiate. Check with your procurement office or counsel, and find state bid portals in RFPhub’s state procurement portals directory.
FAR references are to the text on acquisition.gov as of October 2026. The FAR is being rewritten under the Revolutionary FAR Overhaul, and agencies can apply deviations, so check the current text before relying on a section number. This isn’t legal advice.
How to respond to an ITB
- Get the documents from the official source, and register there so you receive every addendum.
- Read the contract, bond and insurance requirements and the basis of award before you price.
- Attend the pre-bid meeting or site visit. Some are mandatory.
- Ask questions in writing by the deadline, and rely only on written answers and addenda.
- Price exactly what’s specified. Don’t add exceptions or conditions unless the ITB invites them.
- Complete every form. Fill in every price, sign where required, acknowledge each addendum and attach the bid bond.
- Deliver early, by a method the ITB allows.
- Be ready to win. If you’re the apparent low bidder, expect to show you’re responsible and to provide bonds and insurance on time. Report any mistake in your bid at once.
ITBs and software purchases
An ITB is a poor way to choose software, because it can’t weigh features, integrations, security or support. To choose a product, run an RFP, following the RFP process guide.
A price competition fits once the product is chosen: a renewal or extra licenses where the scope isn’t changing, a selected product that several resellers can supply, or hardware to a fixed specification. For these, start from the free RFQ template, which includes a software renewal variant. If your rules require sealed bids at that value, use the same specification in an ITB.
Frequently asked questions
What is an invitation to bid?
An invitation to bid is a formal request for sealed prices on a fully specified requirement, such as a construction project with finished drawings. The contract usually goes to the lowest responsive and responsible bidder.
Is an invitation to bid the same as an RFP?
No. An RFP asks suppliers how they would meet a need and scores their proposals on several weighted criteria. An ITB asks for prices on work already defined, and price decides among bids that meet every requirement.
What is the difference between an ITB and an IFB?
Mostly the name. The FAR uses invitation for bids for US federal sealed bidding, while some states, such as Virginia and Florida, say invitation to bid. The solicitation itself sets the rules that apply.
What does lowest responsive and responsible bidder mean?
A responsive bid meets every material requirement of the invitation. A responsible bidder has the resources and record to do the work. The contract goes to the lowest-priced bid that passes both tests.
Is an invitation to tender the same as an invitation to bid?
Not always. Invitation to tender (ITT) is a common term in the UK and other countries, and tenders may be judged on quality as well as price. Check the ITT’s award criteria to see which kind you have.