The Constitution of Michigan of 1963 Article 9 sec. 3 created the process of equalization. It states:
The legislature shall provide for the uniform general ad valorem (according to value) taxation of real and tangible personal property not exempt by law. The legislature shall provide for the determination of true cash value of such property; the proportion of true cash value at which such property shall be uniformly assessed, which shall not, after January 1, 1966, exceed 50 percent; and for a system of equalization of assessments. The legislature may provide for alternative means of taxation of designated real and tangible personal property in lieu of general ad valorem taxation. Every tax other than the general ad valorem property tax shall be uniform upon the class or classes on which it operates.
Michigan Compiled Law 211.34 (3) implements the constitutional mandate stating:
(3) The county board of commissioners of a county shall establish and maintain a department to survey assessments and assist the board of commissioners in the matter of equalization of assessments, and may employ in that department technical and clerical personnel which in its judgment are considered necessary. The personnel of the department shall be under the direct supervision and control of the director of the tax or equalization department who may designate an employee of the department as his or her deputy. The director of the county tax or equalization department shall be appointed by the county board of commissions. The county board of commissioners; through the department, may furnish assistance to local assessing officers in the performance of duties imposed upon those offices by this act, including the development and maintenance of accurate property descriptions, the discovery, listing, and valuation of properties for tax purposes, and the development and use of uniform valuation standards and techniques for the assessment of property.
The Director of Equalization is also responsible for calculating the millage reduction fractions by the first Monday in June for each unit of government, i.e. schools with in the county intermediate school district, townships, cities villages, and authorities.