X0306 4/A 2020-09-14 2020-09-15 0 0001587732 ONE Gas, Inc. OGS 0001747990 Hart Tracy E 15 E. 5TH STREET TULSA OK 74103 1 0 0 0 Common stock, par value $0.01 2020-09-14 4 P 0 400 69.67 A 2860 D This Form 4 amendment is being filed solely to correct an administrative error in the number of shares of ONE Gas common stock reported in line 1 of Column 5 of Table I in the Form 4 filed on September 15, 2020. The original balance reported in line 1 of Column 5 of Table I in the amount of 4,447 shares inadvertently included 1,587 shares of derivative securities (phantom stock) held by the reporting person under the ONE Gas, Inc. Deferred Compensation Plan for Non-Employee Directors (the "Plan"). Phantom stock is settled in shares of ONE Gas common stock at the distribution date as described in the Plan. /s/ Brian K. Shore, Attorney-in-Fact for Tracy E. Hart 2021-06-08