A visitor who comes to the United States lawfully from another country typically uses what's called a "nonimmigrant visa." For instance, it might be a K-1 visa for the fiancé of a U.S. citizen, an M-1 visa for a vocational program student, or a B-2 visa for a tourist or a visitor for medical treatment. In every such case, the person will, upon entering the U.S., be told by an official of Customs and Border Protection (CBP) the date by which they must depart, and that information will be recorded online, in a form known as an I-94.
But what happens if someone stays in the U.S. beyond that permitted date? U.S. immigration law builds in various consequences for people who overstay their visa or permitted U.S. stay, as described here.
Your period of authorized stay in the United States is the amount of time you are allowed to remain in the country. As mentioned, it is normally found on your I-94 document. At one time, I-94s were issued on paper cards, but they are now, in most cases, accessible via the I-94 page of the U.S. Customs and Border Protection (CBP) website.
Don't make the mistake that some people do and assume that the expiration date on your visa shows the date by which you must leave the United States. A visa is primarily an entry document. It might last a lot longer or a lot shorter a time than you are actually allowed. In fact, it's not uncommon for a foreign national's visa to run out before the I-94 does (except in cases of multiple entry visitor visas, which typically last for several years). Again, you can stay within the U.S. until the date on your I-94.
Depending on the type of visa you have and its terms, you might be able to extend your stay past the date originally permitted. For example, if you are in the U.S. for a job, and your employer wants to continue hiring you, and extensions are allowed on your visa, you could apply for one. Extension applications must be submitted to U.S. Citizenship and Immigration Services (USCIS) before the expiration of your period of authorized stay. In most cases, extensions are requested by filing USCIS Form I-539.
What if you file for an extension but USCIS waits to approve it until after the end date of your period of authorized stay? This is not an unlikely scenario; USCIS is often backed up with applications. If you filed your extension application on time (before your authorized stay period ran out), and USCIS eventually approves it, your period of stay will automatically be extended from the previous end date. This happens regardless of whether USCIS approves the extension before or after the end date. This way, you don't end up with any gaps in your period of authorized stay.
If USCIS does not approve your extension application, however, you will be expected to leave the U.S. immediately.
It's unlikely, but possible that you could be apprehended by U.S. immigration authorities when overstaying the date by which you were supposed to leave the United States. (It would, however, take a huge squad of officials to chase after every U.S. entrant to make sure they all leave on time.)
If you are apprehended, however, you would be placed into removal proceedings. In the absence of any defense to deportation, would be ordered removed from the U.S. and barred from returning for a number of years.
If you overstay your period of authorized stay in the U.S.—even by one day— then it will be automatically cancelled. What's more, you will trigger what is known as the consular shopping bar. This comes from Section 222(g) of the Immigration and Nationality Act (I.N.A.), which states that if you remain inside the U.S. beyond your period of authorized stay, your visa will be cancelled and no longer valid for entry. Additionally, if you want to apply for another visa to the U.S., you will be required to do so at the U.S. consulate in your country of nationality.
Before the consular shopping bar was enacted, many foreign nationals who overstayed simply went to consulates in Mexico or Canada to apply for another period of stay or a new visa. But now, unless you can show that extraordinary circumstances apply to your case, you must reapply for a visa at the consulate located in your country of nationality.
Also, if you applied for an extension and were denied, you won't trigger the consular shopping bar so long as you had good reasons for requesting an extension; that is, your extension request was not frivolous.
Let's say you become eligible for a U.S. green card, for example by marrying a U.S. citizen or receiving a job offer from a U.S. employer. You're thinking it would be convenient to take care of all your paperwork in the U.S., without leaving, using a procedure known as "adjustment of status."
Realize, however, that most applicants must have entered the U.S. with permission, after inspection by border agents, and must be in valid visa status at the time of their application if they are to be eligible to use the adjustment of status procedure. You cannot (with a few exceptions) have have stayed past the expiration of your permitted stay or worked without permission from U.S. immigration authorities.
That doesn't mean such applicants can never get a green card. Leaving the U.S. and applying through what's known as "consular processing" is still a potential option, though could be complicated by the unlawful presence inadmissibility bar described below.
Also, there's an important exception for the immediate relative (children, spouse, or parents) of U.S. citizens. As long as they entered the United States in valid visa status (as opposed to crossing the border illegally) and they didn't use a visa fraudulently with the intent to apply for a U.S. green card after arriving), they may use "adjustment of status" as the procedure by which to apply for their green card even after an overstay.
Anyone who stays continuously in the U.S. without a proper visa for more than 180 days but less than 365 days and then leaves is barred from returning to the U.S. for three years. Harsher yet, someone who stays illegally for a year or more and then leaves cannot come back for ten years.
This doesn't affect everyone. First, someone who was under age 18 for any of the time in the U.S. unlawfully need not count that time toward these bars. Nor does any illegal time before April 1, 1997, or for less than 180 continuous days (even after April 1997) count. Other, narrower exceptions or special situations exist. And it's possible to ask for a waiver of this bar.
For more information, see Consequences of Unlawful Presence in the U.S.—Three– and Ten-Year Time Bars.
If you have overstayed a U.S. visa, but want to spend more time in the United States in the future you'll want to get help from an immigration attorney in analyzing your situation and preparing any necessary waiver or other applications.