In general, the public holidays of the state of Baden-Württemberg apply. In addition, the period around Christmas and New Year from December 24th to January 6th (which is a public holiday in BW) is generally lecture-free. The Pentecost week is also lecture-free.

The current periods for semester duration, lecture period, lecture-free period can also be found on the KIT website [1]

[1] https://www.sle.kit.edu/english/imstudium/697.php