The historic parish of Tveit had to be divided into two formannskapsdistrikts on 1 January 1838 because the main part of Tveit belonged to the county of Lister og Mandal and the annex of "Birkenæs" belonged to the county of Nedenæs and the new law said a municipality could only exist in one county, not two. Therefore, the parish was split and Birkenæs municipality was created in Nedenæs county. On 1 January 1883, an uninhabited part of Birkenes was transferred to the control of neighboring Landvik municipality.