Yamhill County assessor explains Measure 50, change property ratio and how redevelopment can shift McMinnville tax rolls

Derek Wharf, Yamhill County assessor, told the McMinnville City Council at a work session that Oregon’s property-tax rules created by Measure 50 and the annual change property ratio (CPR) drive how new construction and redevelopment are added to the tax rolls.

Wharf said three values — real market value (RMV), maximum assessed value (MAV) set under Measure 50 in 1997, and the assessed value (the lower of RMV and MAV) — determine what is taxable. He explained that the CPR is calculated from the gap between RMV and MAV on existing properties by property type; that percentage is then applied to new construction in a given year to set the MAV for that new construction.

The assessor used examples and a $15 million multifamily case to show how phased construction is added to the roll and how different CPRs produce very different taxable values: “If in 2024 the CPR for multifamily was 0.5 and we put on $9,000,000 then $4,500,000 would go on the MAV line,” Wharf said. He noted multifamily CPRs had fallen sharply in recent years — he cited multifamily CPRs down to about 0.35 in 2024–25 and single-family CPRs in the 0.5–0.6 range, from highs near 0.85–0.9 earlier in the decade.

Why it matters

Wharf told councilors that exception events — new construction,…