(a) Any municipality issuing obligations under any law may issue obligations bearing interest at a single rate or at rates varying from year to year which may be lower or higher in later years than in earlier years. Such higher rate for any period prior to maturity may be represented in part by separate coupons designated as additional coupons, extra coupons, or B coupons, but the highest aggregate rate of interest contracted to be so paid for any period shall not exceed the maximum rate authorized by law. Such higher rate may also be represented in part by the issuance of additional obligations of the same series, over and above but not exceeding two percent of the amount otherwise authorized to be issued, and the amount of such additional obligations shall not be included in the amount required by section 475.59 to be stated in any bond resolution, notice, or ballot, or in the sale price required by section 475.60 or any other law to be paid; but if the principal amount of the entire series exceeds its cash sale price, such excess shall not, when added to the total amount of interest payable on all obligations of the series to their stated maturity dates, cause the average annual rate of such interest to exceed the maximum rate authorized by law. This section does not authorize a provision in any such obligations for the payment of a higher rate of interest after maturity than before.
(b) Any municipality issuing obligations under any law may sell original issue discount obligations having a stated principal amount in excess of the authorized amount and the sale price, provided that:
(1) the sale price does not exceed by more than two percent the amount of obligations otherwise authorized to be issued;
(2) the underwriting fee, discount, or other sales or underwriting commission does not exceed two percent of the sale price; and
(3) the discount rate necessary to present value total principal and interest payments over the term of the issue to the sale price does not exceed the lesser of the maximum rate permitted by law for municipal obligations or ten percent.
(c) Any obligation may bear interest at a rate varying periodically at the time or times and on the terms, including convertibility to a fixed rate of interest, determined by the governing body of the municipality, but the rate of interest for any period shall not exceed any maximum rate of interest for the obligations established by law. For purposes of section 475.61, subdivisions 1 and 3, the interest payable on variable rate obligations for their term shall be determined as if their rate of interest is the lesser of the maximum rate of interest payable on the obligations in accordance with their terms or the rate estimated for such purpose by the governing body, but if the interest rate is subsequently converted to a fixed rate the levy may be modified to provide at least five percent in excess of amounts necessary to pay principal of and interest at the fixed rate on the obligations when due. For purposes of computing debt service or interest pursuant to section 475.67, subdivision 12, interest throughout the term of bonds issued pursuant to this subdivision is deemed to accrue at the rate of interest first borne by the bonds. The provisions of this paragraph do not apply to general obligations issued by a statutory or home rule charter city with a population of less than 7,500, as defined in section 477A.011, subdivision 3, or to general obligations that are not rated A or better, or an equivalent subsequently established rating, by Standard and Poor's Corporation, Moody's Investors Service or other similar nationally recognized rating agency, except that any statutory or home rule charter city, regardless of population or bond rating, may issue variable rate obligations as a participant in a bond pooling program established by the league of Minnesota cities that meets this bond rating requirement.