Contractor Paperwork

Field guide

Addendum vs Change Order in Construction

An addendum commonly changes bidding documents before contract execution. A change order modifies an existing construction contract after it is signed.

Timing is the practical dividing line, but the project documents control. Addenda clarify or revise what bidders are pricing; change orders document an authorized change to contracted work, cost, or time. Keep every issued addendum with the bid record and every signed change order with the executed contract.

Open prefilled generator

Treat addenda as part of bid preparation

Before award, an addendum can revise drawings, specifications, bid dates, clarifications, or other bidding documents. Bidders should review and acknowledge every issued addendum so the price reflects the same information.

Treat change orders as contract administration

After execution, use the contract's change procedure for additions, deletions, credits, or time adjustments. State the changed work and the agreed effect on price and schedule instead of relying on a revised drawing alone.

Preserve the document chain

The final contract record should show which addenda were incorporated at award and which later changes were approved during construction. This prevents the same revision from being priced twice or omitted from closeout.

Decision table

Before award or after execution?

QuestionAddendumChange order
Typical timingBefore contract executionAfter contract execution
What it modifiesBidding or proposed contract documentsThe signed construction contract
Primary audienceProspective biddersContract parties and project administrators
Price effectIncluded in the bid or proposalAdjusts the existing contract sum when agreed
Record locationBid and procurement fileContract modification log

Next step

Put the workflow into practice

Review the construction change order templateSee what to document when the contract already exists.Change order vs. amendmentCompare the specialized project-change path with broader contract amendments.Create a free change order PDFDocument an agreed post-contract change for a contractor and client.
CO-001

One revision at two project stages

Example
Pre-bid addendum
Drawing A-4 is revised to add two windows before contractor pricing is due.
Bid response
Each bidder acknowledges the addendum and includes the windows in the proposed price.
Post-award request
After contract execution, the owner asks to add a third window.
Change order
The parties document the additional window, added price, schedule effect, and approval.

What this example covers

Acknowledge all bid addenda before submitting a price
Carry accepted addenda into the executed contract record
Use the signed contract's change process after award
Do not perform extra work from an informal revision alone

More field paperwork

Related contractor guides

Change order exampleRemodeling change orderRoofing change orderHandyman change orderLandscaping change orderChange order vs invoice

Primary references

Check the governing documents

These references explain common document workflows. Your signed contract and applicable law control your project.

Important note

This is practical paperwork guidance, not legal advice. Review important construction documents with qualified counsel before use.