Most applicants who have been present in the United States for more than 180 days after the expiration of their valid immigration status (or after entering unlawfully) may be declared inadmissible.
Waivers are generally available for unlawful presence inadmissibility, but not to individuals who enter or attempt to re-enter the United States illegally after being unlawfully present for one year or more. In the context of adjustment of status or immigrant visas, unlawful presence waivers are only eligible to applicants who have a U.S. citizen or lawful permanent resident spouse or parent.
It is also important to note that departing the United States after being unlawfully present will trigger a bar to re-entry if a waiver application is not granted. If the period of unlawful presence prior to departure was between 180 days and one year, a three-year bar to re-entry will be imposed. If the period of unlawful presence was greater than one year, a 10-year bar will be triggered. These consequences are especially critical to consider in cases where the applicant must depart the United States to apply for a visa and a waiver.