On 1st April 2023 four of the five Somerset District Councils merged to create Somerset Council. The four are South Somerset, Mendip, Sedgemoor and Somerset West & Taunton. North Somerset remains a separate council.
At present many of the existing contact details remain as they were and many processes are yet to be merged. Planning for instance is still separate system but you would access it from the main Somerset Council website.
www.somerset.gov.uk