It shall be the duty of the department of revenue, and it shall have power and authority:
Wis. Stat. § 73.03
The supreme court in Metropolitan Associates v. City of Milwaukee, 2011 WI 20, held the amendment of sub. (2a) by 2007 Wis. Act 86 to be unconstitutional and severed from the remainder of the statute. Prior to the amendment by Act 86, sub. (2a) read:
(2a) To prepare and publish, in electronic form and on the Internet, assessment manuals. The manual shall discuss and illustrate accepted assessment methods, techniques and practices with a view to more nearly uniform and more consistent assessments of property at the local level. The manual shall be amended by the department from time to time to reflect advances in the science of assessment, court decisions concerning assessment practices, costs, and statistical and other information considered valuable to local assessors by the department. The manual shall incorporate standards for the assessment of all types of renewable energy resource systems used in this state as soon as such systems are used in sufficient numbers and sufficient data exists to allow the formulation of valid guidelines. The manual shall incorporate standards, which the department of revenue and the state historical society of Wisconsin shall develop, for the assessment of nonhistoric property in historic districts and for the assessment of historic property, including but not limited to property that is being preserved or restored; property that is subject to a protective easement, covenant or other restriction for historic preservation purposes; property that is listed in the national register of historic places in Wisconsin or in this state's register of historic places and property that is designated as a historic landmark and is subject to restrictions imposed by a municipality or by a landmarks commission. The manual shall incorporate general guidelines about ways to determine whether property is taxable in part under s. 70.1105 and examples of the ways that s. 70.1105 applies in specific situations. The manual shall state that assessors are required to comply with s. 70.32(1g) and shall suggest procedures for doing so. The manual or a supplement to it shall specify per acre value guidelines for each municipality for various categories of agricultural land based on the income that could be generated from its estimated rental for agricultural use, as defined by rule, and capitalization rates established by rule. The manual shall include guidelines for classifying land as agricultural land, as defined in s. 70.32(2) (c) 1g., and guidelines for distinguishing between land and improvements to land. The cost of the development, preparation, and Internet publication of the manual and of revisions and amendments to it shall be paid from the appropriation under s. 20.566(2) (bm).
The Department of Revenue's construction of a tax law in an official technical information memorandum estopped the department from collecting a tax. DOR v. Family Hospital, 105 Wis. 2d 250, 313 N.W.2d 828 (1982). The Department of Revenue's subpoena authority does not permit it to take possession of subpoenaed records for more than one business day; however, the department may repeatedly subpoena records until its investigation is completed. State v. Kielisch, 123 Wis. 2d 125, 365 N.W.2d 904 (Ct. App. 1985).