Minn. Stat. § 273.056

If after electing in accordance with section 273.055 , the board of county commissioners shall determine that the interests of the county may be better served through valuation by local assessors, it may revoke the election. Such revocation may not be made within four years after the election. In the event of revocation, it shall be effective at the second assessment date following such revocation. The offices of all township and city assessors shall be filled as provided by charter or law 90 days before such effective date.