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As a shareholder in Reinhart’s Tax Practice, Don Millis leverages his extensive experience, knowledgeable team and network of connections to help clients realize their potential through successful tax strategies. He leads the largest tax litigation practice in Wisconsin and serves as co-chair of the firm’s Government Relations Group. Don represents all manner of businesses, including many national firms, in resolving property tax, sales/use tax and income/franchise tax disputes.

He is committed to working with each client and taxing authority to resolve matters at a minimal cost. When they can’t arrive at a satisfactory solution, he moves to effective and efficient litigation strategies. These strategies have consistently saved his clients millions of dollars in state and local taxes. Don’s clients include many large, national companies as well as local and regional businesses facing challenging tax assessments by the state or local government.

Clients appreciate Don’s straightforward advice and professional demeanor in fostering collaboration. He thrives in defending the rights of businesses, shareholders and employees to pursue free enterprise without excessive tax burdens.

Don is a former member and chair of the Wisconsin Tax Appeals Commission (1995 to 2004), the agency that resolves disputes between the Wisconsin Department of Revenue and taxpayers involving income tax, sales and use tax, property tax and real estate transfer fees. He represents clients before local and state assessors, the Tax Appeals Commission, circuit courts, the court of appeals and the Wisconsin Supreme Court. He also has extensive experience working in the legislature on tax and related policy and lobbying the legislature and the Wisconsin Department of Revenue on all aspects of tax law.

Don is currently chair of the Wisconsin Elections Commission, the state agency that oversees elections in Wisconsin. This is Don’s second stint on the Elections Commission. He previously served as a member and chair the State of Wisconsin Elections Board, a predecessor agency to the Elections Commission.

Don is president of WE International, a nonprofit organization that fights poverty and injustice in Africa. He travels to Africa to assist with various programs and, in 2018, joined a team to climb Kilimanjaro as part of an effort to raise awareness of gender-based violence.

Along with his advocacy work, Don enjoys hiking, biking and spending time with his wife and five children.


  • J.D., cum laude, University of Wisconsin Law School
  • B.A., University of Wisconsin-Madison (Journalism and Political Science)

Bar Admissions


Court Admissions

  • U.S. District Court, Western District of Wisconsin


  • Successfully represented the state’s largest business organization in a Wisconsin Supreme Court case forcing the department of revenue to issue tax guidance with administrative rules
  • Represented North America’s two largest shopping mall REITs
  • Successfully represented Wheaton Franciscan Healthcare before the Wisconsin Supreme Court in a property tax dispute with the City of Wauwatosa, securing a property tax refund of approximately $8.4 million
  • Obtained the two largest nonutility property tax refunds–both in excess of $2 million–in Wisconsin history on behalf of two different Fortune 500 companies
  • Successfully represented Walgreen Co. in Walgreen Co. v. City of Madison, a major property tax case decided by the Wisconsin Supreme Court
  • Secured a contested property tax exemption for a specialty hospital
  • Negotiated a $23 million reduction in the property tax assessment for a single condominium development
  • Obtained successive reductions in the property tax assessment of an apartment complex at less than the complex’s purchase price
  • Successfully defended a national telecommunications company against a class action suit brought on behalf of hundreds of thousands of customers alleging the company had unlawfully charged sales tax on its services
  • Represents the entire portfolio of Wisconsin properties for a number of Wisconsin businesses and property owners
  • Spent several years working on policy in the Wisconsin Senate, gaining experience and insight in both the legislative and executive branches of government
  • Practiced complex commercial litigation; his court skills set him apart from many other tax practitioners

Honors & Affiliations

  • Best Lawyers in America® – Lawyer of the Year, Tax Law (2014)
  • Best Lawyers in America® – Best Lawyers (Tax Law)
  • Selected for inclusion in Wisconsin Super Lawyers
  • Institute of Professionals in Taxation
  • Wisconsin State and Local Tax Club
  • International Association of Assessing Officers
  • State Bar of Wisconsin
  • Western District of Wisconsin Bar Association
  • Dane County Bar Association
  • Wisconsin Elections Commission (Chair)
  • Wisconsin Tax Appeals Commission (former chairperson)
  • Wisconsin State Elections Board (former member and chairperson)
  • Safe Communities in Madison (former Board Member) 
  • WE International, Inc. (Board President)
  • Lake Waubesa Bible Camp (President)
  • Affordable Dental Care (Board Member)

News & Insights


  • “Is This the ‘New Normal?’ Distinguishing Between Temporary and Permanent Impacts of the Pandemic,” ABA/IPT Advanced Tax Seminar, March 17, 2022
  • Institute for Professionals In Taxation, annual property tax seminar in Palm Springs, California; Orlando, Florida; and Seattle, Washington
  • International Association of Assessing Officers, annual legal seminars in San Francisco, California and Chicago, Illinois
  • American Game Breeders Association, annual convention in Nashville, Tennessee
  • Frequent speaker at the National Association of Property Tax Attorneys, Chicago, Illinois