You should file a dual-status return if you were a non resident on 31st December.
You must file 1040-NR if you are a dual-status taxpayer who gives up residence in the United States during the year and who is not a U.S. resident on the last day of the tax year.
Write "Dual-Status Return" across the top of the return.
Attach a statement to your return to show the income for the part of the year you are a resident. You can use Form 1040, U.S. Individual Income Tax Return as the statement, but be sure to write "Dual-Status Statement" across the top.
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Dual-status Return
