How to write an addendum to a lease<br>Understand the purpose of an addendum. An addendum is an addition to an already agreed upon contract. The addendum can be used to add to, subtract from, or compliment the agreement that is already in place.
The addendum is written before the lease.
Because an addendum by definition adds onto/modifies the extant lease in some way, the lease must be written first. The system seems not to understand the order of writing is important.