A taxpayer with a balance due on their return will have to pay a failure-to-pay penalty when they O O O O Understate their tax by the larger of $5,000 or 10% of the correct tax. Show negligence or disregard of the rules or regulations, causing an underpayment. Fail to pay the tax owed by the due date. Fail to file the return by the original due date. Mark for follow up