C.R.S. § 38-12-701: Notice of rent increase.

(1) Notwithstanding any other law, in a nonresidential tenancy of one month or longer but less than six months in which there is no written agreement between the landlord and tenant, a landlord may increase the rent only upon at least twenty-one days' notice to the tenant.

(2) (a) Notwithstanding any other law, in a residential tenancy in which there is no written agreement between the landlord and tenant, a landlord may increase the rent only upon at least sixty days' written notice to the tenant.

(b) A landlord shall not terminate a residential tenancy in which there is no written agreement by serving a tenant with a notice to terminate tenancy with the primary purpose of increasing a tenant's rent in a manner inconsistent with this section.