A lot of people are unaware of the difference between the visa expiration date and the date of expiration of their authorized period of stay. To travel to the U.S. you must hold a passport and a valid U.S visa. You need to get the right type of visa based on the purpose of your trip to the U.S. With a visa, you can travel to a U.S. port of entry. Immigration officers at the port of entry will decide how long you may stay in the U.S. and permit you to enter the country.
Visa expiration date
The date on which your U.S. visa will expire will be printed on your visa. The expiration date printed on the visa is not the same as the time you are permitted to stay in the U.S. For example, if you hold a visa that is valid for a ten year period, you may travel back and forth to the U.S. during that ten year period. It does not mean that you can stay here for ten years.
Length of stay in the U.S.
Once you reach a U.S. port of entry, you will be required to complete and submit Form I-94, Arrival/Departure Record. This form registers arrivals and departures of non-immigrants. All the non-immigrants arriving at sea, land and air ports of entry need to complete this form. Immigration officers at the ports of entry will ask you few questions about the purpose of your trip and then grant you entry into the U.S. They will write on your arrival/departure record, the date on which you must leave the U.S. You can stay in the U.S. only till the date indicated on Form I-94. You must not overstay your authorized period of stay. In case you need to stay in the U.S. for longer, you need to file an application for extension of your stay.
Extend your stay
At the time of filing for an extension, you need to show that you have not exceeded your authorized stay. To extend your stay, Form I-539, Application To Extend/Change Non-immigrant Status must be filed, well in advance. In case you stay here beyond the authorized time, you will fall out of status. In this case, your visa will be canceled. You may also use Form I-539 in case you want to change your visa category. For example, if you first entered the country on a B-2 tourist visa and if you wish to study in the U.S., you must file Form I-539 to change your non-immigrant status prior to the expiration of your stay.