I am an international student in US. if I buy products online using my debit card and my online purchases and wire transfer in (my family transfers me tuition from back home directly in my account and send me some expense money through western union) that exceeds $10k in a 12 month period, am I supposed to report this to IRS or FinCen? Is everyone who receives and spends more than $10k required to report to IRS in USA?
No. You only have to report income to the IRS. The money in question is not income. The $10,000 FinCen limit you’ve heard about is for cash transactions only, not electronic transfers.
There is one other limit that might be relevant, which is for gifts. For a giver and recipient within the U.S., gifts below $15,000 don’t have to be reported. Above that they must be reported by the giver, not the recipient. For gifts from outside the U.S., the rules are different (because the U.S. has no jurisdiction over the giver) and I think they are dependent on the source country.
You are required to report to the IRS your income, such as from work or employment. As a student you may not need to file a tax return at all (your university advisor may be able to clarify).
Financial institutions are generally required to report transactions over $10,000 per month to FinCEN, but this is not anything you need to worry about - they report, not you. However, if your bank suggests that you break up a transaction into smaller amounts so they have less paperwork to fill in, that is a bad idea.
If you are a "US Person" for tax purposes you are required to report all of your foreign accounts to FinCEN if the aggregate value of your foreign bank accounts exceeded $10,000 throughout the calendar year. That means if you have a savings account back home, you will need to report that. However you may not be a “US Person” as a student.