Polk County shifts tillable land valuations to CPI-based factors; county medians move toward state target

Polk County assessors outlined a shift in how tillable land will be valued for the 2026 assessment year, telling the Board of Appeal and Equalization that the county used sales and crop productivity index (CPI) mapping to compute local CPI factors and apply them to parcel-level valuations.

"This board of appeal and equalization is for the appeal of the valuation of property, not for appealing the real estate tax," Mark Lansburg told the board as he opened the assessment presentation, and he walked members through the new methodology. Lansburg said staff compute a local CPI factor by dividing sale price per acre by the weighted average CPI for that sale, then apply a township'level typical factor (blended when needed) to estimate tillable market value for parcels.

As an example, Lansburg used a Rome township sale that produced a local factor near 72: a sale at $6,633 per acre with an average CPI of 92 yielded a local factor of about 72. Lansburg said the county examined up to three years of sales, preferred arms-length ("good") sales, and excluded sales meeting the state's rejected-sale criteria (family transfers, government, unadvertised sales, etc.). He explained that the state property tax compliance officer can review county choices and require changes if statewide ratios warrant.

Staff said the county also implemented a practical floor and cap for CPI-based valuation: parcels with CPI below 50 were valued at the 50 CPI rate (with a noted exception for wild rice parcels) and those with CPI above 95 were capped at 95. Lansburg said this approach improved statistical measures (medians and coefficient of dispersion) in bracketed ratio studies.

The presentation included broader context: Lansburg cited a national housing-price index (HPI of 326.48 for 2026) and reviewed city and township sales ratios across Polk County. He reported that after applying changes the county median moved from roughly 88% to 96%, with some townships and rural residential classes closing the gap toward the state'guided range (commonly described as 90% to 105% in staff materials). Lansburg said the state issued no corrective order for Polk County in 2026.

Why it matters: moving to a CPI-based approach for tillable land aims to align valuations with observable sales and productivity measures while reducing abrupt discrepancies across townships. County staff emphasized transparency and said the method was chosen to be explainable to property owners and defensible to state review.

What comes next: Lansburg and assessor staff encouraged property owners to review ratio maps and contact the assessor's office with questions; the county will notify property owners of final decisions after appeals and follow its normal letter-notification process for outcomes.