All international students who were in the U.S. for one or more days in 2023 are required to fill out certain tax forms. Even if you did not work or receive income in the U.S., you are still required to file Form 8843 with the IRS.
Meanwhile, if you earned any taxable U.S. source income, you may need to file a federal tax return with the IRS. Depending on your individual circumstances, you may also need to file a state tax return(s).
Both federal AND state taxes must be postmarked by April 15, 2024.