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Contracts & Legalaka: addenda (plural)

Addendum

In Plain English

An official written change to the bid documents issued before bids are due.

Definition

An addendum is a written document issued by the owner or designer before bid submission that modifies, clarifies, or supplements the bid documents. All addenda become part of the contract documents upon execution. Bidders must acknowledge receipt of all addenda in their bid submission or the bid may be rejected as non-responsive.

Why It Matters in Bidding

Addenda directly alter the scope, quantities, or schedule a contractor is pricing, so a missed addendum can mean bidding the wrong drawings and either losing money or being disqualified. In competitive bidding, failing to acknowledge every addendum on the bid form makes a bid non-responsive and grounds for rejection, regardless of price. Late addenda also commonly extend the bid deadline, which affects how estimators sequence pricing and subcontractor quotes.

Example

Two days before bids were due, the architect issued Addendum No. 3 deleting a curtain wall section and substituting storefront glazing, forcing the GC to rescind its original glazing sub quote and reprice the revised scope.

Related Terms

Bid DocumentsBidding DocumentsResponsive BidderModification

Frequently Asked Questions

Most bid forms require listing each addendum number received. Omitting one signals the bidder may have priced outdated documents, so owners can reject the bid as non-responsive even if it is the lowest. On public projects this rejection is often mandatory, making addendum acknowledgment a critical compliance step.
An addendum modifies the bid documents before bids are submitted and applies equally to all bidders, so everyone prices the same revised scope. A change order modifies an already-executed contract during construction and adjusts the contract sum or time. The key distinction is timing: addenda are pre-award, change orders are post-award.
The owner or the design professional, typically the architect or engineer of record, issues addenda, often in response to bidder questions submitted during the request-for-information period. They distribute addenda to all registered planholders to keep the playing field level, and each addendum becomes part of the final contract documents.

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