Congestion charge and environmental differentiation is introduced because of the Oslo-package 3 agreement that was negotiated in the spring of 2016 between the parties Oslo commune, Akershus provenance commune, Jernbaneverket and Statens vegvesen. The agreement has also been decided by the Parliament in June 2017. The Parliament also decided the Additional-agreement of June 13. 2017, which specifies the changes in the toll rate system in three steps towards 2020.