A new, updated draft of the Standard on Ratio Studies was released to IAAO members for comment and feedback during a 30-day exposure period starting May 1, 2026. The Research and Standards Committee will now review comments prior to presenting to the Board of Directors.
Updates to the IAAO’s Standard on Ratio Studies were last approved in 2013. In 2025, Research and Standards released an initial rewrite of the standard, which was the culmination of several years of collaboration.
Following the release, the committee conducted an extensive outreach campaign, which included three Fair+Equitable articles, a conference presentation, an episode of the Assessing the Situation podcast, and two webinars.
Based on comments received, the committee made substantial revisions to the draft standard and is seeking comments on the revised draft. In April, the IAAO Board of Directors approved releasing the exposure draft for comment.
Draft – Standard on Ratio StudiesThere were significant changes to the draft, particularly in the area of vertical equity, along with updates to the COD Standard Ranges, and substantial revisions to the appendices, including new appendices. A summary of changes made to the first draft is available online.
The Exposure Draft represents the committee’s work and is not to be considered a final document. The 2013 version remains the recommended guidance until a final version, edited to reflect stakeholder feedback, is approved by the IAAO Board.