What is an Addendum?

Definition: An addendum is an additional piece of information added to a given document. It is a supplementary section added after the original text is done.

What Does Addendum Mean?

The word addendum comes from the Latin and it can be translated as “something added”. The term is mostly employed in the legal field to describe a portion of new clauses or text being added to a legal document in order to modify its previous information. This new additions can change the document’s purpose and nature substantially and they can also modify its reach and impact on the parties involved.

This is the reason why addendums, in order to be considered valid, need to be signed by each party to declare their acceptance of the new information being added to the document. This means that addendums are normally drafted after an initial document is already signed.

The addendum, then, must be attached to the original piece for the parties to understand the final purpose and reach of the document. Addendums have been used in occasions for fraudulent purposes. Given the misleading nature of having a document that changes a previous one, the contract’s trace can be lost and the contractual relationship can change its nature without one of the parties noticing the change.


A company called Lovely Views LLC. provides apartment space for rent to individuals and corporations. The company is currently leasing a 100mt2 apartment in the downtown area of a big city in the U.S.

Mr. Gonzalez is interested in this apartment to move into the city and he contacted Lovely Views to see the apartment. After he saw it he said to be happy with the offer and willing to sign for it. The company drafted the lease agreement and explained Mr. Gonzalez everything he needed to know about the contract and the property.

A few days later, the company’s representative called Mr. Gonzalez to tell him that he needed to sign an addendum where all the inventory that is inside the apartment is described, in order to declare that he has received this equipments in good shape and must return them in the same condition when the contract is due. This would be an example of an addendum, since it would be an additional piece of information written and added to the original document which, in this case, would be the lease agreement.