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( Mark One ) ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31 , 2020 Commission File Number 1-8962 1-4473 UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON , D.C. 20549 TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from PINNACLE WEST CAPITAL CORPORATION ( an Arizona corporation ) 400 North Fifth Street , P.O. Box 53999 Phoenix Arizona ( 602 ) 250-1000 Securities registered pursuant to Section 12 ( b ) of the Act : Exact Name of Each Registrant as specified in its charter ; State of Incorporation ; Address ; and Telephone Number PINNACLE WEST CAPITAL CORPORATION Securities registered pursuant to Section 12 ( g ) of the Act : ARIZONA PUBLIC SERVICE COMPANY FORM 10 - K ARIZONA PUBLIC SERVICE COMPANY ( an Arizona corporation ) 400 North Fifth Street , P.O. Box 53999 Phoenix Arizona ( 602 ) 250-1000 Large accelerated filer Emerging growth company Title Of Each Class Common Stock , No Par Value OR PINNACLE WEST CAPITAL CORPORATION 85072-3999 ARIZONA PUBLIC SERVICE COMPANY Common Stock , Par Value $ 2.50 per share 85072-3999 Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act PINNACLE WEST CAPITAL CORPORATION ARIZONA PUBLIC SERVICE COMPANY to PNW Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Act . PINNACLE WEST CAPITAL CORPORATION ARIZONA PUBLIC SERVICE COMPANY Accelerated filer Trading Symbol Yes Yes Yes Yes □ Non - accelerated filer New York Stock Exchange X No No No No Indicate by check mark whether each 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 . PINNACLE WEST CAPITAL CORPORATION Yes Yes No No ARIZONA PUBLIC SERVICE COMPANY Name Of Each Exchange On Which Registered 0 0 Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site , if any , every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S - T during the preceding 12 months ( or for such shorter period that the registrant was required to submit and post such files ) . PINNACLE WEST CAPITAL CORPORATION Yes Yes ARIZONA PUBLIC SERVICE COMPANY No No 0 0 Indicate by check mark whether the registrant is a large accelerated filer , an accelerated filer , a non - accelerated filer , 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 . IRS Employer Identification No. 86-0512431 ■ 86-0011170 Smaller reporting company