The Taxpayer is registered with the Department for payment of monthly CRS taxes. The Taxpayer’s bookkeeper was late preparing the CRS return for the October 2000 reporting period, and the return was hand-delivered to the Department one day after the statutory due date. The Department assessed the Taxpayer for penalty and interest on the late payment. The Taxpayer protested the assessment, arguing: (1) the state did not suffer any loss of revenue because the Department received the Taxpayer’s hand-delivered payment on the same day that it would have received a timely payment mailed on the statutory due date; (2) the Taxpayer should be given the benefit of the amendment to Section 7-1-67 NMSA 1978 which became effective January 1, 2001, that requires interest on late payments to be calculated on a daily-rather than a monthly-basis, and (3) the Taxpayer has an exemplary reporting history and should be allowed one mistake without having to pay penalty and interest. Held: (1) the version of Section 7-1-67 in effect at the time the tax was due requires imposition of interest whenever payment is not made by the statutory due date. The Department is not authorized to substitute its judgment for that of the legislature or give retroactive effect to amendments to the state’s tax laws. The Taxpayer was negligent in failing to pay its taxes on time, and penalty was properly assessed pursuant to Section 7-1-69 NMSA 1978. Protest denied.