your calculations will be wrong for a1040. any balance owed was due 5/17/2021. let the IRS figure it. if it's small enough they might not even bill you because the cost of sending out the bill would be more than the bill itself. also, we're not sure what penalty you're referring to. there is a penalty for underpayment of estimated taxes and a different penalty for not paying the balance due by the 5/17/2021 due date. Turbotax only calculated the estimated tax penalty.
