According to the National Election Commission, 26 by-elections will be held along with the 18^th Presidential Election on December 19. These include 1 election for the head of Si/Do Government, 1 election for the Superintendent of Education, 3 elections for the head of Gu/Si/Gun Government, 2 elections for Si/Do Council members and 19 elections for Gu/Si/Gun Council members.

A by-election will be held following the resignation of the head of Do Government in Gyeongsangnam-do while a repeat election for the Superintendent of Education is to be conducted in Seoul. In addition, 3 elections for the head of Gu/Si/Gun Government are scheduled to be held in Jung-gu Incheon-si, Dong-gu Gwangju-si and Gyeongsan-si Gyeongsangbuk-do. Furthermore, 2 elections for Si/Do Council members are due to be conducted in the constituencies located in Dongducheon-si, Gyeonggido while elections for Gu/Si/Gun Council members are to be held in 19 constituencies including the constituency A in Jungrang-gu, Seoul.

Generally the law prescribes that a repeat or by-election shall take place on the last Wednesday in October. The repeat/by-elections, however, will be held at the same time as the 18^th Presidential Election on December 19 in accordance with Article 203 Clause 3 of the Public Official Election Act as the elections are scheduled within 40 days before the starting date of the 18^th Presidential Election period.

In case elections take place simultaneously, the election management shall be carried out, focused on an election whose period is longer. The repeat/by-election will be managed in the same manner as the Presidential Election in terms of the period for registering candidates & absentee voters, the absentee voting period, the period for sending out election campaign leaflets, voting hours and so forth.

The Election Commissions produce different colored ballot papers to help voters residing in the corresponding constituencies to easily distinguish different types of elections. Different colored papers will be used in the following elections:

Presidential Election : white,

Head of Si/Do Government : yellowish green,

Superintendent of Education : light slate-gray,

Head of Gu/Si/Gun Government : sky-blue,

Si/Do Council members : egg-colored, and

Gu/Si/Gun Council members : mayonnaise-colored