How is the national electoral register created?

Act No. 333/2004 On Elections to the National Council of the Slovak Republic, Sections 4, 5, 6, 7, 8

The national electoral register is not created by the Slovak Republic. Instead, a permanent register of electors is compiled and maintained by each municipality. The voter lists are updated continuously and are based on the municipalities’ own records and information provided by the state institutions. Municipalities may use and update the information contained in the population register maintained by the Ministry of Interior.