IAAO's History, Vision & Mission

About Us

IAAO is a nonprofit, educational, and research association. It is a professional membership organization of government assessment officials and others interested in the administration of the property tax. IAAO was founded in 1934, and now has a membership of more than 8,500 members worldwide from governmental, business, and academic communities.

Vision Statement

IAAO is to be recognized as a diverse and inclusive global leader and preeminent source of standards, professional development, and research in mass appraisal, technical assistance, assessment administration, and property tax policy.

Mission Statement

IAAO is a global community of diverse mass appraisal professionals advancing fair and equitable property appraisal, assessment administration, and property tax policy through professional development, research, standards, and technical assistance.


IAAO was first formed as a national body in 1934 when John C. Donehoo, the city assessor for St. Petersburg, Florida, called together a group of municipal and county assessors to consider the formation of a new group that would serve to train and educate assessment professionals, work toward a more equitable assessment system, and focus on a revision of property tax legislation as a remedy for the Depression, then at its height. Mr. Donehoo served as the Association’s first president.

After some changes to the official organization’s name, it became the National Association of Assessing Officers (NAAO). In 1959, the name was changed to the International Association of Assessing Officers (IAAO) to reflect the growth of non-U.S. members.

With the establishment of membership categories in 1934, affiliate and chapter memberships were created. The first NAAO chapter was granted to New York City in 1938.

Educational development was a key priority during the early growth of the Association with goals to improve the professional standing of assessors, and to provide better training. The Association’s Professional Designation Program was inaugurated in 1952, conferring a Certified Assessment Evaluator (CAE) designation to IAAO members who demonstrated an acceptable degree of competence in the assessing field.

IAAO publications as an educational resource began early. In 1937, the Association was solicited by a Wisconsin assessor to distribute a report on property tax administration in Wisconsin. IAAO’s first periodical was first published in 1937. Aside from the monthly newsletter, the association’s first member publication was the Standard Practice Series, which debuted in 1938. This series eventually developed into the association’s assessment standards that are still published as Technical Standards by IAAO today.

Information services were not limited to publications, and early in its history the IAAO started to build a library with an intention to serve as a leading source of information on property taxation and assessment administration. The IAAO Inquiry Answering Service remains one of the most valuable information resources today.

In the late 1970s and early 1980s, IAAO technical and consulting services provided yet another way to elevate the high standards of assessment practice.

The IAAO headquarters offices were located in Chicago from the 1930s until 2005 when the Association moved to its present location in downtown Kansas City, Missouri.