RSA 21-J:32 Penalty for Underpayment of Estimated Tax.

I. Except as provided in paragraph IV, in the case of any underpayment of estimated tax by a taxpayer, there shall be added to the tax for the taxable period an amount determined at the underpayment rate as determined from time to time pursuant to RSA 21-J:28, II, on the amount of the underpayment for the period of the underpayment.
II. For the purposes of paragraph I, the amount of the underpayment shall be the excess of:
(a) The amount of the installment which would be required to be paid if the estimated tax were equal to 90 percent of the tax for the taxable period; over
(b) The amount, if any, of the installment paid on or before the last date prescribed for payment.
II-a. For purposes of this section, "taxable period" means the calendar year or fiscal y