From the IRS website: If you don't have to file a 2016 tax return, mail Form 8843 to the Department of the Treasury, Internal Revenue Service Center, Austin, TX 73301-0215 by the due date (including extensions) for filing Form 1040NR or Form 1040NR-EZ.
Form and instructions can be found here: https://www.irs.gov/pub/irs-pdf/f8843.pdf
