The Electoral Commission of Queensland (ECQ) will conduct local government by-elections at Ipswich on Saturday, 19 August.
The poll follows the resignation of Mayor Paul Pisasale earlier this month.
ECQ's Director of Elections Wade Lewis said the Ipswich by-election would be a significant event.
"More than 120,000 people are enrolled to vote in the Ipswich council area so we'll have around 350 staff operating 40-plus polling booths on election day," Mr Lewis said.
"Ipswich residents will also be able to vote early at one of the three pre-poll centres that will be open from August 7.
The Electoral Commission is urging people living in the council area to ensure they are properly enrolled to vote.
"Voting is compulsory so anyone who turned 18 or became an Australian citizen since the last election must enrol to vote," Mr Lewis said.
"And people who have changed their name, address or other contact details need to go to ECQ's website or phone us to make sure their enrolment information is up to date."
The official Notices of Election are set to be issued on 15 July 2017.
Timetable for the by-election can be viewed at ecq.qld.gov.au