You will be considered a resident alien if you have completed five years on an F1 visa.
Otherwise, you will have to file a nonresident return 1040NR and you will have to file form 8843 along with your tax return.
OPT is also considered on F1 visa.
If you are a nonresident alien filing Form 1040NR, you may be able to use one of the three filing statuses: Single, Married Filing Separately (MFS), or Qualifying Widower
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1040NR
