Administrative composition of the village
Since their establishment until the end of 1922, Tlmače belonged to the Tekov (Borš) county (“župa”) and the Slúžnovský castle in Levice. After cancellation of historical Hungarian regions, Tlmače became part of the Levice district and XVIII – Zvolen region in the period 1923 – 1928. At the Slovak state, Tlmače belonged to the Hron County (Pohronská župa).
From 1929 to 1938, Tlmače fell under the District office (OU) in Levice. After the Vienna arbitration they were assigned to OU in Pukanec (where the district administration seat was temporarily moved from Levice). Afterwards, Tlmače were attached to OU in Zlaté Moravce and since liberation they have belonged to Levice district, which was incorporated into the Nitra County.
In line with the act of the Slovak National Council No. 13/1970 Coll. on territorial division of the Slovak socialistic republic, floor of the District national council in Levice decided on its meeting on 27 September 1985 about merging of villages Tlmače – Veľké Kozmálovce and Malé Kozmálovce to single political municipality – Tlmače.
Tlmače were declared a city with effect from 1 January 1986.
Based on results of votes of population living in part Malé Kozmálovce on 10 June 1994 and Veľké Kozmálovce on 10 July 1994, these parts were separated from the city of Tlmače.