Colorado law 39-1-104 (10.2) (a) C.R.S. requires a two-year reassessment cycle for all property. Reappraisal years occur on every odd-numbered year. We will mail a Notice of Valuation around May 1. Each notice will describe the property you own and give the value for the last two years. You have the right to appeal your value each year regardless of value changes. May of each year is set aside for the Assessor’s office to hear appeals on real property valuations.