Addendum vs Amendment

In tendering, an addendum is issued before the closing date and becomes part of the solicitation documents; an amendment usually changes something after award — most often the contract.

Addendum — pre-closing

Buyers publish addenda to answer bidder questions, correct errors, change scope or quantities, extend the deadline, or add mandatory requirements. Addenda go to all registered bidders simultaneously, and most solicitation forms require you to acknowledge every addendum in your bid — skipping an acknowledgement is a common compliance failure.

Amendment — post-award

Once a contract exists, changes run through contract amendments: scope changes, time extensions, price adjustments. Public buyers cap cumulative amendments (commonly a percentage of original value) — beyond the cap, many policies require a new competitive process instead of another amendment.

Why the distinction bites suppliers

Tracking addenda is a bid-stage duty: bid without the latest addendum's changes and your price or method is stale. Tracking amendments is a contract-stage duty: perform to the amended document, and bill against amended terms. Confusing the two in correspondence slows approvals and disputes.

Common questions

Do buyers use the words interchangeably?

Some do — "amendment No. 3" sometimes appears before closing. Check the date and content: if it modifies the solicitation documents before closing, treat it as an addendum functionally.

Can an addendum extend the closing date?

Yes, and it is the only binding way it can change. An email or phone call extending the deadline is not binding unless confirmed in an addendum.

Where do I see addenda?

Attached to the original notice on the buyer's portal. pubsec.pro links notices to their documents so bidders can check for updates before bidding.

Related definitions

Tender notice · RFP meaning · Bid bond vs performance bond