Minn. Stat. § 216B.63: INTEREST ON ASSESSMENT.

The amounts assessed against any public utility not paid after 30 days after the transmittal of a notice advising the public utility of the amount assessed against it, draw interest at the rate of six percent per annum; and, upon failure to pay the assessment, the attorney general shall proceed by action in the name of the state against the public utility to collect the amount due, together with interest and the cost of the suit.