Addendum – Definition

Cite this article as:"Addendum – Definition," in The Business Professor, updated October 22, 2019, last accessed October 25, 2020,


Addendum Definition

An addendum refers to a material or document attached to a contract which provides more details on an original information contained in the contract. Addendum can be used in different contexts, it can be used for a legal contract, book publication or a written work. When used in a contract, an addendum is a document attached to the main contract that provides clarity or modify some information in the contract.

In certain cases, an addendum is a document that provides additional information that were not included in the original contract.

A Little More on What is an Addendum

When an addendum is attached to a piece of writing, it is a document showing supplemental information added to the original document. It also shows a change, modification or clarification added to the initial piece of writing or an original document. Regardless of the form an addendum takes, it alters a contract in the sense that it is a change or modification to the initial agreement.

When used in a contract, an addendum is binding and all parties to a contract must consent to or sign an addendum. This means that all the parties must agree to the modification made to the initial agreement.

Examples of Addendums in Use

There are diverse instances of addendums being used in real life scenarios and real contracts. Depending on the industry or type of contract in question, the party that issues an addendum may differ. For instance, it is a client that issues an addendum in the construction industry, when issued, the addendum becomes a part of the contract.

In the real estate industry, an addendum can be used in a lease or purchase agreement usually to supply details of the financing terms of the property and other issues not contained in the original purchase or lease agreement.

Addendums and Amendments

Addendum serves diverse functions in the context of an agreement, contract or an original draft. An addendum is used to provide clarification, modification or nullification of certain information contained in the contract. Due to the purpose an addendum serves, it is sometimes likened to amendment.

An addendum can also be called an amendment when it alters or changes a part of an original draft or an agreement. Hence, when an addendum brings about a change to an already existing document, it is an amendment. This existing agreement or contract can be that of an executed contract or one that is still being processed. In the construction industry for example, amendment is common or constant, a project in the work can be amended to suit the desires of a client while an executed project can also be amended to achieve desired results.

Reference for “Addendum”

Academics research on “Addendum”

Initiating IPD Concepts on Campus Facilities with a” Collaboration Addendum”, Franz, B., & Leicht, R. M. (2012). Initiating IPD Concepts on Campus Facilities with a” Collaboration Addendum”. In Construction Research Congress 2012: Construction Challenges in a Flat World (pp. 61-70). Integrated project delivery (IPD) is attracting the attention of owners, seeking a more collaborative, shared risk, design and construction environment for high-performance building projects. However, the administration of a tri-party or multi-party contract requires a high level of owner involvement and experienced contractors. For owners considering an IPD approach, but unable or unprepared to pursue a multi-party agreement, several “IPD-lite” options are being tested within the construction industry. This research uses quasi-experimental observational case studies of four campus facility projects to follow the progress of the Pennsylvania State University’s facility management organization, the Office of Physical Plant (OPP), through the development and implementation of a Collaboration Addendum as a supplementary contract attachment. Since the selected case studies are planned using traditional delivery methods, the Addendum was designed to integrate desired characteristics of an IPD approach, including: early involvement of project participants, collaborative decision-making, collocation and a performance-based incentive program. The development of the attachment followed a three step procedure of (1) defining the collaborative intent, (2) refining the intent on a project or team-specific basis and (3) outlining the desired process for achieving meaningful collaboration. Metrics for assessing the success of the Addendum were developed to determine the effectiveness of achieved levels of collaboration and included performance measures of timeliness of communication and meeting effectiveness. This paper reports the development and in-process implementation of the Addendum on selected case study facilities, as a means of promoting collaborative team behavior.

ConsensusDOCS 301 BIM addendum, Lowe, R. H., & Muncey, J. M. (2009). ConsensusDOCS 301 BIM addendum. Constr. Law., 29, 17.

ADDENDUM I, Manual, I. M. S. S. O., & Attachment, E. (1993). ADDENDUM I. INLINE INC.

Interpreting the NFL Player Contract, Roberts, G. R. (1992). Interpreting the NFL Player Contract. Marq. Sports LJ, 3, 29.

Outcomes of family counseling interventions with children who resist visitation: An addendum to Friedlander and Walters (2010), Johnston, J. R., & Goldman, J. R. (2010). Outcomes of family counseling interventions with children who resist visitation: An addendum to Friedlander and Walters (2010). Family Court Review, 48(1), 112-115. Preliminary findings on the outcomes of family‐focused counseling interventions for alienated and estranged children are presented based upon data from a longitudinal study of children in chronic custody disputes who were interviewed as young adults and from the clinical records of long‐term therapy with these children who were resisting visitation.

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