Tender addendum vs contract amendment

A tender addendum changes the solicitation documents before the closing date; a contract amendment changes a signed contract after award. Same word family, opposite sides of the closing line — and confusing them is expensive in both directions.

Tender addendum — before closing

An addendum is the buyer's official instrument for changing a bid solicitation after it is issued: answering questions, correcting errors, changing scope or specifications, or extending the closing date. Once issued it becomes part of the solicitation documents, and most solicitations require bidders to acknowledge receipt of each addendum with their bid. Under Canadian tendering law, a compliant bid creates what courts call "Contract A" (the process contract) at submission — per the Supreme Court of Canada in R. v. Ron Engineering (1981) — so only changes published through a proper addendum bind everyone fairly. An email promise or a phone call to one bidder does not.

Contract amendment — after award

Once the contract exists, changes run through contract amendments: scope changes, time extensions, price adjustments, added deliverables. Amendments need the agreement of both parties in writing. Public buyers usually cap how much the total value can grow through amendments — past the cap, most policies require a new competitive process rather than another amendment, because pushing everything through amendments undermines competition.

A naming wrinkle on federal solicitations

Federal buyers often use the word "amendment" for the pre-closing instrument. Shared Services Canada's standard instructions say "Canada will issue an amendment to the solicitation" for any clarifications or changes, and CanadaBuys tender notices post these under an Amendments tab — without notifying bidders individually. So on a federal RFP, "Amendment 2" dated before closing is functionally an addendum. Read the date, not just the label: anything issued before the closing date modifies the solicitation documents; anything after award modifies the contract.

Common questions

Do I have to acknowledge every addendum?

Check the solicitation's instructions. Where acknowledgement is mandatory, a bid that misses one is usually declared non-compliant and never evaluated. Bidders — not the buyer — are responsible for checking the tendering platform regularly for amendments, per federal standard instructions.

Can an addendum extend the closing date?

Yes — that is the only binding way it can change. An addendum published on the platform re-sets the deadline for everyone; individual email extensions are not enforceable against other bidders.

Can the buyer amend the contract without my agreement?

Contracts usually give the buyer a limited unilateral right to make administrative changes or order modest scope changes, with price and schedule adjusted through agreed processes. Material changes beyond the contract's change provisions need a real amendment — or a new solicitation.

Related definitions

Addendum meaning · Change order · RFP meaning · Tender notice