New directives effective August 9, 2018
A student visa is basically a visa until the end of your studies. This period is called Duration of Status (D/S). People who enter the US on a student visa will have their passport stamped with D/S.
Your stay is legal as long as the Form I-20 is valid. The question of “When does a stay become illegal?” in regards to instances where illegal activities are committed has been clarified.
In the past, it has been considered as an illegal stay from the point of a decision being made in court, even if the offence was apparent beforehand.
Following the new directives effective August 9, 2018 onwards, the Immigration Department counts a stay as illegal from the date it determines an illegal activity has been committed, without waiting for a court judgment.
For example - someone has been working illegally for 6 months and been discovered by the Immigration Department. It is not counted as an illegal stay from the day the Immigration Department finds out about the illegal activity. If the Immigration Department determines that you have been committing an illegal activity for six months, those past six months will be counted retroactively towards your illegal stay.
If it has been determined that you have stayed illegally for 180 days, you will be prohibited from entering the United States for three to ten years. You will be prohibited from entering the United States for periods any longer than a year.