thanks for the response.

But from Pub 519 page 46-50 Dual status filing, it says "must file by 4/15.

I am confused, anyone can help? Appreciated!

When and Where To File:
1. If you are a resident alien on the last day of your tax year
and report your income on a calendar year basis, you
must file no later than April 15 of the year following the
close of your tax year (but see the TIP, later). If you report
your income on other than a calendar year basis, file your
return no later than the 15th day of the 4th month following

the close of your tax year. In either case, file your return
with the address for dual-status aliens shown on the back
of the Instructions for Form 1040.
2. If you are a nonresident alien on the last day of your tax
year and you report your income on a calendar year basis,
you must file no later than April 15 of the year following the
close of your tax year if you receive wages subject to withholding. If you report your income on other than a calendar year basis, file your return no later than the 15th day of
the 4th month following the close of your tax year. If you
did not receive wages subject to withholding and you report your income on a calendar year basis, you must file
no later than June 15 of the year following the close of
your tax year. If you report your income on other than a
calendar year basis, file your return no later than the 15th
day of the 6th month following the close of your tax year. In
any case, mail your return to:
Department of the Treasury
Internal Revenue Service
Austin, TX 73301-0215