In the real world, it's not uncommon for people who are well past their teens or twenties to want to obtain a college degree. Perhaps they weren't able to before due to the expense or other personal matters. But if you are hoping to do so as a foreign student coming to the United States on an F-1 visa, expect to have a little more trouble than others getting a visa for this purpose. Your age, and any other indicators that education was not previously high on your priority list, could work against you, for the reasons described below.
Applicants for an F-1 visa are always up against the tendency of the U.S. government to believe that most people are just looking for a way to come to the United States in order to stay forever. Meanwhile, an intent to return home at the end of one's studies is part of the basic eligibility requirements for the F-1 visa.
It's up to applicants to prove that they're genuinely interested in and qualified to pursue the activities for which the particular visa was designed, and that they will leave the United States at the end of the permitted stay. (For more information on student visa eligibility and the application process, see the Student and Exchange Visitor Visas section of Nolo's website.)
But someone who's older than the average student might already has a full and settled life, perhaps a job and family; thus leading the U.S. government to wonder why they want to interrupt everything in order to study abroad.
As if the above weren't difficult enough, U.S. Citizenship and Immigration Services (USCIS) has specifically listed, among its student visa fraud indicators, "age is not commensurate with education sought" and "education request doesn't correlate with beneficiary's employment background."
Actually, you might be applying through the U.S. State Department rather than USCIS if you're coming from abroad, but this USCIS statement likely reflects a common pattern seen by the State Department as well.
If a reason for your delay in applying for an F-1 student visa was your past inability to afford your period of time as a student in the United States, that could be an issue as well, if your financial situation hasn't turned around completely. You will need to show that you can cover tuition, room, board, and living expenses. This will require a hefty amount of savings at most U.S. colleges and universities, and you will not be allowed to count on accepting employment in the U.S. to help cover these costs. (See When F-1 Students Can Work in the U.S.)
An on-campus job is acceptable to U.S. immigration authorities, and you can probably qualify for paid training work, but these don't tend to pay much.
The above discussion shouldn't be taken to mean that getting an F-1 student visa will be impossible. You are, however, likely going to need an attorney's help in strategizing your arguments and preparing your visa application. You will ideally want to provide actual, documentary evidence, as opposed to your own oral statements, showing the depth of your interest in studying in the U.S. and the reasons you were unable to pursue a college education before now.
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