Addendum Details

If you have a contract or document that you need to update or revise, an addendum is one particularly efficient way to do so. An addendum – or, as it is sometimes referred to as, an ‘appendix’ – is commonly used for everything from straightforward extensions of clarified dates to more complex changes in even the most minute or important details. An addendum may feature diagrams, drawings, or other images for greater clarification as well as additional information. However, suppose these changes are more significant, such as modifications to previously agreed-upon terms and conditions. In that case, both parties must sign the addendum for the updated contract to become a legally binding document.

Stemming from the Latin plural ‘addenda,’ which translates to “must be added,” addendums are intended to be purposefully separated from the document they modify to avoid confusion for all parties involved. Addendums are also timesavers, as they make it so a writer need not rewrite an entire document or contract with every update. As such, addendums significantly cut down on printing costs and environmental impact. Addendums do carry the potential for fraud, however, which is why it is crucially important for both parties to sign off on any changes to the original agreement.

Addendum has several related terms. Here are a few common ones:

  • Appendix: The most common synonym for an addendum, an appendix usually includes tables and is found at the end of books.
  • Annex: An annex is typically much larger than an addendum, featuring large excerpts, tables, and other stand-alone works.
  • Exhibit: Used exclusively in court cases as a means to portray relevant evidence.
  • Attachment/Enclosure: Whereas an attachment refers to files attached within an email, an enclosure refers to any physical material included with a letter.

Real World Example of Addendum

In April of 2021, Southern California issued reopening guidelines for the State’s major amusement parks, such as Disney Land and Universal Studios Hollywood, after being forced to close during the COVID-19 pandemic. The State permitted a time-restricted indoor capacity of twenty-five percent and weekly testing for workers, among other modifications. As a result of an addendum, however, the most notable of these guidelines became the one that declared, “In-state visitors only, check for current CDPH Travel Advisory in effect.”

According to, an addendum to the reopening guidelines clarified that “Fully vaccinated persons from out of State may visit or attend activities or events that are restricted to in-state visitors. Fully vaccinated persons should consult the current CDPH Travel Advisory and adhere to any applicable recommendations.” Yet, because the CDPH Travel Advisory says out-of-staters do not have to test for COVID-19 unless they show symptoms, park operators became hesitant about welcoming visitors outside California.

Further, park operators were also unclear about what exactly was impacted by the addendum. “Indoor live events or concerts” were reportedly excluded while, confusingly, similar “activities and events” like movie theatres, museums, zoos, and aquariums were not. Indeed, it’s evident that sometimes an addendum intended for clarification can, if not handled delicately, sow even greater confusion instead.