What is visa waiver?
A current list of visa waiver countries for the Czech Republic.
If you are from a visa waiver country, then you are able to stay in the Czech Republic/Schengen zone for up to 90 days without the need for a visa.
You can stay as long as you do not work during the 90 days.
You are allowed to be in the Schengen zone 90 days in 180 days.
The days are free for you to choose and use. One month in, one month out, whatever.
If you are here for 90 days continually, then you would have to leave and stay out of the Shcengen zone for 90 days.
The 90 days rule is enforced. If you are found to have overstayed or worked during your visa waiver period you stand the chance of being deported at you own expense and being banned from Europe for some years.
If you plan on working on the Czech Republic the you will need a work permit and visa.
90 day visa waiver
The actual 90 day visa free time is controlled and counted. If you over stay you time it can cause problems. That is the nice way to say it. In reality if you over stay your 90 days you become illegal. And you are then granted the rights accorded to any illegal immigrant.When do the 90 days start and finish?
The 90 days start when your passport is stamped at the point of entry into the Schegen zone.The 90 days "clock" stops ticking when you leave Schengen.