(1) A tax levied under any state tax law which is not paid when due is delinquent. Interest at the rate of ten percent (10%) per annum shall be collected on the total tax deficiency from the date the return for the tax was due to be filed until the date of payment;

(2) Interest on a tax deficiency shall be assessed at the same time as the tax deficiency. The tax deficiency together with the interest shall be paid upon notice and demand by the director;

(3) When any overpayment has been made by a taxpayer, the overpayment shall be refunded together with interest at the rate of ten percent (10%) per annum;

(4) Interest on overpayments shall be paid from the date the return for the tax was due to be filed or the date the return is filed, whichever occurs later, until a date, to be determined by the director, preceding the date of the refund warrant by not more than thirty (30) days, whether or not the warrant is accepted by the taxpayer;

(5) No interest shall be allowed on an overpayment of tax that is refunded by the director within ninety (90) days after the last date provided for filing the return for the tax including any extension of time for filing the return, or ninety (90) days after the date the return is filed, whichever occurs later; and

(6)

(A) In lieu of the amount of interest otherwise provided by this section, when an election to defer the payment of estate tax is made pursuant to the provisions of § 26-59-113(c), then the amount of interest on the deferred portion of the estate tax qualifying for the election shall be at the rate of four percent (4%) per annum on the balance of the payments due under the installment deferral election.

(B) However, the four percent (4%) interest rate shall only apply to the "4-percent portion" as that term is defined in 26 U.S.C. § 6601(j)(2), as it existed on January 1, 1989.

(C) The interest rate on the estate tax exceeding the "4-percent portion" shall be at the rate specified in subdivision (1) of this section.