Originally Posted by pingpong abyss

(I) Minors.-No period of time in which an alien is under 18 years of age shall be taken into account in determining the period of unlawful presence in the United States under clause (I)."

However, once you turn 18, you start to accrue presence. By 180 after your eighteenth birthday, you will have acquired a three year ban from the country, which will be initiated once you leave the U.S. Once you have accrued one year of unlawful presence, that will become a ten year ban. If you leave the country while you have the three year ban and attempt to enter within three years, the ban will become a ten year one. If you leave the country with the ten year ban and attempt to enter within ten years, that will become a permanent ban and will not be waivable until you have been outside of the country for ten years.