Chaudandigadhi is a municipality out of four municipalities of Udayapur District of Province No. 1 in Nepal. It was formed by merging some village development committee (VDC) with Beltar Basaha Municipality. The VDCs merged with it are: Chaudandi, Siddhipur, Hadiya and Sundarpur. The total area of the new formed municipality is 283,78 km². The total population of the municipality is 48,574. The municipality was formed on 10 March 2017. It is surrounded by Belka Municipality in east, Triyuga in west, Khotang and Bhojpur in north and Sunsari District in south.
Chaudandigadhi Fort is a historical place in Udayapur district situated at an altitude of about 1040 meters from sea level. The fort is around 360 years old built by Sen Dynasty. At the later period of unification of Nepal to the Tista on the east this fort as well as the Sen Kingdom was dissolved on Nepal. This fort is about 20-22 Km north and takes about 1.5 hours drive on muddy road from Municipality centre Beltar. The fort is situated on ward no. 1 of Chaudandigadhi Municipality. Pleasant weather and scenic viw attracts the visitor here.