Minnesota State Statutes grant the Assessor's staff authority to view and assess property.
273.20 ASSESSOR MAY ENTER DWELLINGS, BUILDINGS, OR STRUCTURES
Any officer authorized by law to assess property for taxation may, when necessary to the proper performance of duties, enter any dwelling-house, building, or structure, and view the same and the property therein.
Any officer authorized by law to assess property for ad valorem tax purposes shall have reasonable access to land and structures as necessary for the property performance of their duties. A property owner may refuse to allow an assessor to inspect their property. This refusal by the property owner must be either verbal or expressly stated in a letter to the county assessor. If the assessor is denied access to view a property, the assessor is authorized to estimate the property's estimated market value by making assumptions believed appropriate concerning the property's finish and condition.
274.01 BOARD OF REVIEW
Subdivision 1. (b) ...On application of any person feeling aggrieved, the board shall review the assessment or classification, or both, and correct it as appears just. The board may not make an individual market value adjustment or classification change that would benefit the property in cases where the owner or other person having control over the property will not permit the assessor to inspect the property and the interior of any buildings or structures.