Addendum
Also known as: addenda · bid addendum
An 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.
Addenda are issued during the bidding period, often in the final days before the due date, and sometimes several in a week. Each one is numbered.
Why you must acknowledge them
Bid forms almost always require you to list the addenda you received by number. Failing to acknowledge one signals that you may have priced superseded documents — which can get a bid set aside as non-responsive, particularly on public work where responsiveness rules are strict.
Addendum vs. change order
An addendum changes the documents before bids are due, so it is priced into your bid. A change order changes the work after a contract exists, and is priced separately as additional or credited work. Confusing the two is an expensive mistake in both directions.
Related terms
- Invitation to BidAn 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.
- Change OrderA change order is a written amendment to an existing contract that adds, removes, or modifies work, and adjusts the contract price and schedule accordingly. It applies after a contract is in place — unlike an addendum, which changes the documents before bids are due.
- Scope of WorkA scope of work defines exactly what a subcontractor is and is not responsible for on a project. In a bid proposal it is usually expressed as inclusions, exclusions, and qualifications — and it determines whether extra work becomes a change order or an unpaid dispute.