The Colorado Unclaimed Property Act can be found at 38-13-101. Please refer to the law for specific requirements. In the Due Dilligence section, CRS 38-13-110(5).
It can also be found in the instructions for the annual General Reporting
information. It states, "The Law requires businesses to try to locate the
owner. Not more than 120 days before filing the unclaimed property report, for property in the amount of $50.00 or more, the holder shall send written notice to the appraent owner's last known address stating that property is behing held and may be turned over to the State Treasurer