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UNITED STATES SECURITIES AND EXCHANGE COMMISSION □ ANNUAL REPORT PURSUANT TO SECTION 13 OR WASHINGTON , D.C. 20549 Form 10 - K 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31 , 2020 or □ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Delaware ( State or other jurisdiction of incorporation or organization ) Commission file number 1-37774 AdvanSix Inc. ( Exact name of registrant as specified in its charter ) 300 Kimball Drive , Suite 101 Parsippany , New Jersey ( Address of principal executive offices ) Registrant's telephone number , including area code ( 973 ) 526-1800 Securities registered pursuant to Section 12 ( b ) of the Act : Title of each class Common Stock , par value $ 0.01 share per Trading Symbol ASIX 81-2525089 ( I.R.S. Employer Identification No. ) 07054 ( Zip Code ) Name of each exchange on which registered New York Stock Exchange Securities registered pursuant to Section 12 ( g ) of the Act : None Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . Yes o No Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Exchange Act . Yes o No | Indicate by check mark whether the Registrant ( 1 ) has filed all reports required to be filed by Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 during the preceding 12 months ( or for such shorter period that the Registrant was required to file such reports ) , and ( 2 ) has been subject to such filing requirements for the past 90 days . Yes No Indicate by check mark whether the Registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S - T ( § 232.405 of this chapter ) during the preceding 12 months ( or for such shorter period that the registrant was required to submit such files ) . Yes No Indicate by check mark whether the Registrant is a large accelerated filer , an accelerated filer , a non - accelerated filer , a smaller reporting company , or an emerging growth company . See the definitions of " large accelerated filer , " " accelerated filer , " " smaller reporting company , " and " emerging growth company " in Rule 12b - 2 of the Exchange Act . ( Check One ) :