An Idaho roommate agreement is a contract, separate from a lease agreement, that defines the terms of a living arrangement between roommates. The document is used to determine how rental costs and utility payments are divided between the roommates and to establish guidelines with regard to behavior on the premises to which all parties agree. Common terms include shared areas, cleaning duties, noise restrictions, prohibited activities, and overnight guests. It is recommended that individuals in a shared tenancy create a roommate agreement to ensure that responsibilities are clearly understood and to avoid unreasonable disputes.