Under Colorado law, a tenant is protected from rent increases only if a lease provides for a fixed rent or a specific rental period. The landlord cannot raise the rent during the period of a lease term unless there is some provision in the lease for such a rent increase. There is no limitation on the amount a landlord can increase the rent at the end of a lease period.

There is no limit on the amount or frequency of rent increases in month-to-month tenancies. In a month-to-month tenancy, the landlord must give proper written notification (no less than ten days before the end of the month for which rent has been or should have been paid) in order to raise the rent for the next rental month. If you don't get proper notice of a rent increase, politely inform your landlord that the law allows the tenant a ten-day written notice before an increase. You will be expected to pay the increase the following month.