Change Order vs Addendum vs Work Authorization
These documents can all contain signatures, but they usually solve different moments: changing existing work, modifying an agreement, or authorizing work to begin.
The label on a form matters less than what the underlying agreement says it does. Still, using the right document type makes the project record easier to understand. A change order, addendum and work authorization should not be treated as interchangeable just because each can have a signature line.
| Change order | Addendum / amendment | Work authorization | |
|---|---|---|---|
| Typical purpose | Modify scope, price, time or responsibilities on an existing job | Add to or modify terms of an agreement | Authorize defined work, access, diagnosis or spending |
| Typical timing | After the original agreement, when the job changes | Before or after execution depending on how the parties/document use the term | Before the authorized work or service activity begins |
| Key content | Changed scope + price/time impact | Exact contract provision or added terms being modified | Authorized task + limit/conditions |
| Best anchor | Original contract / prior scope | Agreement being supplemented or amended | Job/work order/service request |
Change order: the job itself is changing
AIA guidance describes a change order as a document used when the parties have agreed to a change, including the impact on contract sum and contract time. On smaller service projects, the same practical principle is useful even when the business is not using AIA forms: identify what changes and what happens to price and schedule.
Addendum or amendment: the agreement terms are changing
Terminology varies by industry and contract. “Addendum” is sometimes used for information added before contract execution and sometimes more broadly; “amendment” commonly refers to a later modification of contract terms. Follow the terminology and modification procedure used by your underlying agreement rather than relying on a generic internet label.
Work authorization: permission to perform defined work
A work authorization can be the right document before a diagnostic visit, limited repair, access task or service call. It is especially useful when the customer is authorizing work up to a stated limit rather than modifying a fully negotiated construction contract.
The decision rule
- Are you changing an existing project scope, price or time? Start with the contract's change-order process.
- Are you changing a broader contract term? Use the amendment/addendum mechanism the agreement recognizes.
- Are you simply asking permission to perform a defined task? A work authorization may be clearer.
- Does the contract prescribe a form? Follow it rather than substituting a generic PocketESign-generated form.