It's true that you have 3 years from the date the taxes were due to file your federal return and still receive a refund. In Oklahoma, however, they say that you can't get money back that was sent to them more than 3 years ago. So if the last withholding or payment with coupon was sent in December, 2021, and you file in January, 2025 or later, too bad. You are still supposed to file a return though even if it's too late for a refund unless you are exempt.
