Minn. Stat. § 161.084: SURPLUS FUNDS IN TURNBACK ACCOUNTS.

On determining at any time that there are surplus funds in either the county or municipal turnback account that are not needed for the purposes specified herein, the commissioner shall notify the commissioner of management and budget in writing of such determination, and such surplus funds, in the amount specified by the commissioner, shall be transferred to the county state-aid highway fund, or the municipal state-aid street fund, as the case may be, and apportioned as provided by law.