If a U.S. person is granted an extension of time to
file an income tax return, the due date for filing Form 3520
is the 15th day of the 10th month following the end of the
U.S. person’s tax year.
Send Form 3520 to the:
Internal Revenue Service
Center
P.O. Box 409101
Ogden, UT 84409.
Form 3520 must have all required attachments to be
considered complete
Instructions for Form 3520: https://www.irs.gov/pub/irs-pdf/i3520.pdf