AI-assisted research summary: If a taxpayer underpays estimated tax, a penalty applies at the rate set in section 421.7.
1. If the taxpayer submits an underpayment of the estimated tax, the taxpayer is subject to an underpayment penalty at the rate established under section 421.7 upon the amount of the underpayment for the period of the underpayment. 2. The amount of the underpayment shall be the excess of the amount of the installment which would be required to be paid if the estimated tax was equal to one hundred percent of the tax shown on the return of the taxpayer for the taxable year over the amount of installments paid on or before the date prescribed for payment. 3. If the taxpayer did not file a return during the taxable year, the amount of the underpayment shall be equal to one hundred percent of the taxpayer’s tax liability for the taxable year over the amount of installments paid on or before the date prescribed for payment. 4. The period of the underpayment shall run from the date the installment was required to be paid to the last day of the fourth month following the close of the taxable year or the date on which such portion is paid, whichever date first occurs. 5. A payment of estimated tax on any installment date shall be considered a payment of any previous underpayment only to the extent such payment exceeds the amount of the installment determined under subsection 2 or 3 of this section for such installment date. [C79, 81, §422.88; 82 Acts, ch 1180, §4, 9] 95 Acts, ch 83, §11, 36; 2009 Acts, ch 179, §135, 153 Referred to in §422.89