Home 9 About ACS 9 Team


Robert E. Slavin: JD, Antonin Scalia School of Law at George Mason University; BA California State University Northridge. Mr. Slavin founded Assessment Counselling Services (ACS) in 1986 as a full service property tax firm with an emphasis in state & local taxation. He has represented over 10,000 cases before Assessment Appeals Boards or Hearing Officers. Mr. Slavin belongs to the Los Angeles County Bar Association, Taxation section, the International Association of Assessing Officers (IAAO) and the Society of Auditor Appraisers (SAA). Mr. Slavin has been a featured speaker before various organizations and professional associations and has taught continuing education classes for lawyers, CPAs and realtors. In 2001 Robert Slavin successfully ran for the Westlake Village City Council and was re‐elected twice, serving 12 years in the capacity of Mayor, Mayor Pro‐Tem and Councilmember. He was also on the equivalent of the Planning Commission for 10 years. Mr. Slavin works most of his time as a property tax consultant with Assessment Counselling Services, and in special circumstances represents clients through his private law practice, The Law Office of Robert E. Slavin, PC.

John Origer: BA, Humboldt State University. Mr. Origer has over 25 years of experience in the property tax field; he gained significant knowledge with the Los Angeles County Assessor’s Office, where he spent 17 years as an Advanced State Board of Equalization Certified Appraiser. During his time at the Assessor’s Office, Mr. Origer was not only responsible for assessing major regional shopping centers, hotels, office buildings and retail properties; he also presented thousands of cases at the Assessment Appeals Board.

Sean Slavin, CPA: BA, University of California, Santa Barbara.  Mr. Slavin worked in public accounting for several years, servicing both high net worth individuals and business entities before joining ACS in 2018.  Mr. Slavin has experience in income tax preparation, tax planning, estate planning, IRS/FTB audit representation and utilizes those qualities at ACS.  Mr. Slavin primarily works on ownership issues and personal property.  Within personal property he specializes in audit representation and aircraft assessment issues.

Carl M. Lindner: BA, University of California, Santa Barbara. Mr. Lindner has a decade of experience in the property tax field. He started his career with the Los Angeles County Assessor’s Office valuing luxury residential properties; he quickly received his Advanced State Board of Equalization Certification for Appraisal. For most of his career, he was primarily responsible for the valuation of the most valuable properties in Los Angeles County, oil refineries. Mr. Lindner specializes in valuation of all types of real and personal property, as well as complex ownership issues.

Melissa Gosparini, MBA: MBA, Woodbury University; BS Business Administration/Management, California State University, Northridge. Ms. Gosparini has over a decade of experience in the legal field and over half a decade of experience in the real estate industry, her expertise ranging from drafting deeds to foreclosure auctions, risk management, and litigation before joining ACS in 2021. She has extensive experience in ownership and title research, managing client relations and thrives in the complexity of property tax matters.

Robert Cooney: BA, University of Rochester. Mr. Cooney has nearly two decades of experience in the property tax field, having served as an Assessor’s Representative at the Los Angeles County Board of Appeals for five of those years. He obtained his Advanced State Board of Equalization Certification for Appraisal, and has since valued some of the largest, most valuable, and most complex properties in the State of California. He was an appraiser trainer at the County of Los Angeles and prepared special training materials on valuing contaminated properties and dealing with intangible assets in Ad Valorem valuation. He has presented thousands of cases at the Board of Appeals and advised County Counsel on property tax cases in their purview.

Ron Cooper (Emeritus): BA Business Administration, Cal State Fullerton. Mr. Cooper retired from the Orange County Assessor’s Office where he was the Senior Auditor Appraiser in charge of business property appeals. His experience also includes extensive real property appraisals of complex properties. Mr. Cooper has handled hundreds of appeals.



Our firm has represented thousands of taxpayers ranging in size from multi-billion dollar corporations to private individuals. As a result of our expertise and broad range of experience, we have obtained millions of dollars in refunds and tax savings for our clients. Assessment Counselling Services represents a diverse cross section of the business community throughout the state of California.