Invitation to Bid
Also known as: ITB · Invitation for Bid · bid invitation
An invitation to bid (ITB) is a general contractor asking a subcontractor to price a defined scope of work on a specific project. It names the project and location, states a bid due date, and provides access to drawings, specifications, and any addenda issued.
Receiving an ITB is not a commitment by either party. General contractors routinely invite several subcontractors per trade package so they can compare numbers, and on public work they may be required to solicit a minimum number of bids.
Who sends an invitation to bid?
The general contractor does — but the email almost never arrives from their own domain. Most GCs solicit through a platform such as PlanHub, BuildingConnected, ConstructConnect, or Procore, and the invitation is relayed from that platform's address, frequently a per-thread alias like `728832@message.planhub.com`. The contractor's identity appears only in the display name or the body of the message.
What an ITB should contain
- Project name and location, as the GC refers to them
- The bid due date and time, and where to send the proposal
- The scope or trade package you are being asked to price
- Access to drawings, specifications, and the finish schedule
- Any addenda issued to date, and how further addenda will be distributed
- Bid form requirements — alternates, unit prices, allowances
Related terms
- Bid TabA bid tab is the spreadsheet a general contractor's estimator uses to compare every subcontractor bid received for one trade package, line by line, so the numbers can be levelled against each other and the lowest responsible bid identified.
- AddendumAn addendum is a formal change to the bid documents issued by the architect or general contractor before bids are due. It can revise drawings, specifications, quantities, the scope, or the bid date, and it becomes part of the contract documents.
- PrequalificationPrequalification is a general contractor's vetting process that a subcontractor must pass before receiving invitations to bid. It typically reviews insurance coverage, financial capacity, bonding, safety record, licensing, and references from comparable completed projects.