Colorado Anti-Retaliation Law (2026) - C.R.S. § 38-12-509

Colorado's tenant anti-retaliation protection was created by the Residential Tenants Health and Safety Act (HB 19-1170, effective 2 August 2019) and now sits at C.R.S. § 38-12-509. It is a real and useful protection, but it is narrower than it is often described: it is tied to the warranty of habitabilityThe legal promise your landlord makes that the rental unit will be safe and livable — with working heat, plumbing, electricity, and no serious hazards. It applies in most US states whether it's written in the lease or not., and it does not contain a general time-based presumption of retaliation.

• Protected activities (C.R.S. § 38-12-509(1)(a)): (I) raising a warranty-of-habitability issue about the condition of the premises with the landlord, a third party, or a governmental agency; (II) organizing or becoming a member of a tenants' organization; and (III) exercising or attempting to exercise any other right or remedy granted to tenants under the warranty of habitabilityThe legal promise your landlord makes that the rental unit will be safe and livable — with working heat, plumbing, electricity, and no serious hazards. It applies in most US states whether it's written in the lease or not..
• What counts as retaliation (C.R.S. § 38-12-509(1)(b)): increasing rent; decreasing services; terminating or refusing to renew a rental agreement without the tenant's written consent; bringing or threatening to bring an action for possession; charging any fee, cost or penalty; or taking action that intimidates, threatens, discriminates against or harasses the tenant.
• Remedies (C.R.S. § 38-12-509(2)): the tenant recovers damages of not more than three months' periodic rent or three times actual damages, whichever is greater, plus reasonable attorney fees and costs, and may terminate the rental agreement. Note the shape of this: the three-months'-rent figure is a ceiling on that measure, not a guaranteed statutory award.
• Affirmative defense in an eviction (C.R.S. § 38-12-509(1.5)): a tenant may assert retaliation as a defense to the landlord's action for possession — including where possession is sought on a lease violation, a termination notice, lease expiration, or nonpayment arising from a retaliatory rent increase.
• What the statute does not do (C.R.S. § 38-12-509(5)): the prohibition does not stop a landlord from serving a notice to terminate or notice to vacate that is otherwise allowed by Colorado law. Retaliation has to be shown; it is not presumed from timing alone.
• Mobile home parks are different (C.R.S. § 38-12-212.5): park residents do get a timing presumption — management action taken within 120 days after a protected activity is presumed retaliatory, and management must rebut it with evidence of a non-retaliatory purpose. Exceptions apply for nonpayment of rent and for a home reported as an illegal drug laboratory.

On notice: the warranty-of-habitability complaint that usually grounds a retaliation claim does not require certified mail. Under C.R.S. § 38-12-503(2) the landlord has notice through any writing giving a basis to know the condition exists, including a notice sent by the means the landlord typically uses to communicate. Put it in writing anyway — dated, kept, and specific — because you will need to prove both the protected activity and its date.