Whenever in the judgment of the board of county commissioners all taxes authorized to be levied in any one year for general or special county purposes are insufficient to carry on the primary governmental functions, or to pay the mandatory obligations imposed by law upon a county, then such a county may borrow money in an amount the board determines necessary to meet the deficiencies existing in its general or special funds, or to carry on primary governmental functions, and to pay mandatory obligations. For the purpose of borrowing, a county may issue evidences of indebtedness, which must consist of an agreement by the county to pay a stated sum on a specified date, or on or before a specified date, not more than five years in the future, or twenty years for loans issued under section 6-09-49 or 6-09-49.1, together with interest at a rate or rates resulting in an average annual net interest cost not to exceed twelve percent per annum if sold privately, or with no interest rate ceiling if sold at a public sale or to the state of North Dakota or any of its agencies or instrumentalities. A public sale must comply with the procedures set out in chapter 21-03. There is no requirement for an advertisement for bids if an evidence of indebtedness is sold privately or to the state of North Dakota or any of its agencies or instrumentalities.