Colo. Rev. Stat. § 39-3-204
No later than May 1, 2013, and no later than May 1 of each year thereafter in which an assessor sends a notice of valuation pursuant to section 39-5-121 (1)(a) that is not included with the tax bill, each assessor shall mail to each residential real property address in the assessor's county notice of the exemption allowed by section 39-3-203 (1). As soon as practicable after January 1, 2014, and as soon as practicable after January 1 of each year thereafter, each county treasurer shall, at the treasurer's discretion, mail or electronically send to each person whose name appears on the tax list and warrant as an owner of residential real property notice of the exemption allowed by section 39-3-203 (1). The treasurer must mail or electronically send the notice in each year on or before the date on which the treasurer mails the property tax statement for the previous property tax year pursuant to section 39-10-103. No later than May 1, 2008, and no later than each May 1 thereafter, each assessor also shall mail to each residential property address in the assessor's county notice of the exemption allowed by section 39-3-203 (1.5). No later than May 1, 2007, the division shall mail to the residential property address of each person residing in the state who the division believes is a qualifying veteran with a disability notice of the exemption allowed by section 39-3-203 (1.5) for the 2007 property tax year. However, the sending of notice to a person by the division does not constitute a determination that the person sent notice is entitled to an exemption. The notice must be in a form prescribed by the administrator, who shall consult with the division before prescribing the form of the notice of the exemption allowed by section 39-3-203 (1.5), and must include a statement of the eligibility criteria for the exemptions, instructions for obtaining an exemption application, and, for applications for exemptions for property tax years commencing on or after January 1, 2024, instructions for obtaining proof of qualifying veteran with a disability status. To reduce mailing costs, an assessor may coordinate with the treasurer of the same county to include notice with the tax statement for the previous property tax year mailed pursuant to section 39-10-103 or may include notice with the notice of valuation mailed pursuant to section 39-5-121 (1)(a).
C.R.S. § 39-3-204