In the fourth phase, elections will be held in 55 of the 243 assembly constituencies.
The last date for filing nominations for the fourth phase is October 14. While the scrutiny of papers will be held on October 15, candidates can withdraw their nominations till October 17.
Additional Chief Electoral Officer R. Lakshamanan said here that the process for the five-phase assembly elections in Bihar began last month with filing of nomination papers for the first, second phase and third phase early this month.
The constituencies going to polls in the fourth phase are in seven districts - Sheohar, Sitamarhi, East Champaran, West Champaran, Muzaffarpur, Siwan and Gopalganj.
The main contest is between the Bharatiya Janata Party-led National Democratic Alliance and the grand alliance of Janata Dal-United, Rashtriya Janata Dal and the Congress.
Bihar will elect a new 243-member assembly in staggered polls to be held between October 12 and November 5. The counting of votes will be held on November 8.