KRS 136.980

If any tax imposed by KRS 136.330 to 136.395, 299.530 and 304.4-030, whether assessed by the department, or the taxpayer, or any installment or portion of any tax is not paid on or before the date prescribed for its payment, there shall be collected interest upon the unpaid amount at the tax interest rate as defined in KRS 131.010(6) from the date prescribed for its payment until payment is actually made to the department.