You may meet the Czech tax residency day-count test if you spend at least 183 days in the Czech Republic during a calendar year, continuously or across multiple stays. Each started day of presence counts, including arrival and departure days. This is only the physical-presence test: you may also be considered a Czech tax resident based on having a qualifying permanent home in the Czech Republic, and an applicable tax treaty may change the final residency determination.
https://financnisprava.gov.cz/cs/dane/dane/dan-z-prijmu/dotazy-a-odpovedi/dan-z-prijmu-fyzickych-osob/aktualne-k-dani-z-prijmu-fyzickych-osob-2025