All the contesting parties -- Congress, AIUDF, BJP and Independents -- ended their campaign at the stipulated 5 PM.
Altogether 25 candidates are in the fray for the three constituencies where polling will be held from 7 AM to 5 PM, the Election Office said.
Counting of votes will be on September 16.
Silchar has the highest number of 12 candidates followed by Jamunamukh (eight) and Lakhipur (five).
Arun Dutta Majumdar (Congress), Dilip Kumar Paul (BJP) and Nur Ahmed Barbhuyan (AIUDF) are among the prominent contestants in Silchar, while former MLA Dinesh Prasad Goala's son Rajdeep Goala (Cong), Mukesh Pandey (AIUDF) and Sanjay Thakur (BJP) are the noted ones in Lakhipur.
The bye-election was necessitated following the election of Silchar MLA Sushmita Dev and Jamunamukh MLA Mohammad Sirajuddin Ajmal to the Lok Sabha during the last general elections.
The death of sitting MLA Dinesh Prasad Goala necessitated bypoll in Lakhipur.