About the International Association of Assessing Officers (IAAO)
A Trusted Leader in Property Assessment for Over 90 Years
The International Association of Assessing Officers (IAAO) is a nonprofit educational and research organization supporting more than 8,000 property assessors, government officials, and valuation professionals across the United States and around the world.
For more than 90 years, IAAO has helped advance fair, transparent, and consistent property tax systems. Our members serve their local communities by ensuring property values are assessed thoughtfully, accurately, and equitably. Their work plays an essential role in supporting the public services that communities depend on every day.
What IAAO Members Do?
IAAO members are assessment professionals, appraisers, and public officials who determine the assessed value of property for tax purposes.
Their work helps ensure fairness across neighborhoods and builds trust in the property tax system. Using standardized mass appraisal methods, assessors analyze data across large groups of properties to promote consistency and accuracy.
Our History
IAAO was founded in 1934 during the Great Depression, when St. Petersburg, Florida assessor John C. Donehoo brought together local officials to improve training, promote fair property assessments, and strengthen property tax systems. He served as the Association’s first president and helped establish a mission centered on fairness, education, and public trust.
Originally named the National Association of Assessing Officers, the organization became the International Association of Assessing Officers in 1959 to reflect its growing global membership. In its early years, IAAO established local chapters, developed member publications, and introduced professional education programs, including the respected Certified Assessment Evaluator designation.
Continuing the Mission Today
Over time, IAAO has grown into a recognized leader in property assessment standards, research, and professional guidance. Our organization has developed widely used technical standards, built trusted information resources, and expanded consulting services to support jurisdictions in improving assessment practices.
From its early headquarters in Chicago to its current home in Kansas City, Missouri, IAAO has remained committed to strengthening property assessment through education, collaboration, and innovation.
Today, that mission continues. IAAO supports professionals, informs policymakers, and helps communities maintain fair, transparent, and effective property tax systems that serve the public good.