Colorado Revised Statutes Title 39. Taxation § 39-21-109. Interest on underpayment, nonpayment, or extensions of time for payment of tax

(1) If any tax or charge administered pursuant to this article 21 is not paid on or before the last date prescribed for payment, interest on such amount at the rate imposed under section 39-21-110.5, except as provided in subsection (1.5) of this section, shall be paid for the period from such last date to the date paid. The last date prescribed for payment shall be determined without regard to any extension of time for payment and shall be determined without regard to any notice and demand for payment issued, by reason of jeopardy, prior to the last date otherwise prescribed for such payment. In the case of a tax in which the last date for payment is not otherwise prescribed, the last date for payment shall be deemed to be the date the liability for the tax arises, and in no event shall it be later than the date notice and demand for the tax is made by the executive director of the department of revenue or the executive director's delegate.

(1.5) If payment of or an agreement to pay the amount of any tax described in subsection (1) of this section is made within thirty days of notice of underpayment, nonpayment, or extension of time, the executive director shall waive the imposition of the three points in excess of the prime rate described in section 39-21-110.5(2) on such amount unless the executive director determines that there has been a willful neglect or failure to pay such tax.

(2) Interest prescribed under this section shall be paid upon notice and demand and shall be assessed, collected, and paid in the same manner as the tax to which it is applicable.

(3) If any portion of a tax is satisfied by credit of an overpayment, then no interest shall be imposed under this section on the portion of the tax so satisfied for any period during which, if the credit had not been made, interest would have been allowed with respect to such overpayment.

(4) Interest prescribed under this section on any tax may be assessed and collected at any time during the period within which the tax to which such interest relates may be assessed and collected.

(5) This section shall not apply to any failure to pay estimated Colorado income tax.