Once a person overstays their visa by 180 days, but less than 1 year, they can face a three year to reentry, which would commence upon the person leaving the United States. If they overstay by more than 1 year, they can face a ten year bar. This bars remain even after coming back into status subsequently.
Moreover, because the bar does not begin to run until the person leaves the United States, the bar does not expire after three years or ten years. However, in these situations, it is possible to obtain a waiver of the bar. This is requested through the I-601 form. But without the foresight to seek the waiver before leaving the United States, an immigration nightmare scenario can occur.