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Addendum: Definition, Example and Related Terms

What is an Addendum ?

An 'addendum' is a formal, written follow-up to an original contract or agreement. It's like an appendix in a book; it adds extra information or clarifications after the main document is already complete. In the commercial world, an addendum might be used to include additional details about the terms of a deal, specify the scope of work in more detail, or insert new clauses that were agreed upon after the original contract was signed. For instance, if two companies agree to extend the deadline for a project, they might draft an addendum to reflect the new timeline. Or, if they decide to add more deliverables to a service contract, an addendum would specify what those deliverables are and how they affect pricing and deadlines. It's a way to make official changes without rewriting the entire contract.

An Addendum is not to be confused with an amendment. Although they are frequently used interchangeably. An Addendum means additions to the contract. Amendments are changes to exisitng terms that were already agreed.


  • Key Element Description
    Software Licensing Agreement An addendum here could include the terms for additional software features or services that were not initially covered in the original contract.
    Commercial Lease Agreement An addendum to a lease might outline the use of a newly available adjacent space or common area facilities that the tenant can access, not originally part of the lease.
    Service Level Agreement (SLA) An addendum could be used to add new services or support terms that were not included in the original SLA.
    Joint Venture Agreement An addendum could specify a new project or initiative that the joint venture will undertake, which was not mentioned in the original agreement.
    Non-Profit Sponsorship Contract An addendum here might add a new event or program to be sponsored, which was not included in the initial sponsorship agreement.