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( Mark One ) UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10 - K × ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31 , 2020 ог For the transition period from □ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 to Commission file number 0-13222 CITIZENS FINANCIAL SERVICES , INC . ( Exact name of registrant as specified in its charter ) Pennsylvania ( State or other jurisdiction of incorporation or organization ) 15 South Main Street , Mansfield , Pennsylvania ( Address of principal executive offices ) Registrant's telephone number , including area code : Securities registered pursuant to Section 12 ( b ) of the Act : None ( 570 ) 662-2121 Securities registered pursuant to Section 12 ( g ) of the Act : Common Stock , par value $ 1.00 per share ( Title of class ) Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . 23-2265045 ( I.R.S. Employer Identification No. ) 16933 ( Zip Code ) □ Yes ☑ No Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Act . Yes ☑ 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 .: Large accelerated filer Non - accelerated Filer ☑ Accelerated filer Smaller reporting company Emerging growth company