If you are owed a refund, nobody cares when you file. What you must do timely is *pay*. To be more precise, the penalty for late filing is a formula based on what you owe. If you owe $0, the penalty is $0. Sadly the penalty does not go into negative numbers, so they won't pay you if they owe you! After April 15, 2022, you forfeit a right to a refund. So focus on sending a payment to the state timely! You can use your stare's version of a Form 4868 as a payment coupon. Postmark in the mail is good enough.