Colorado: Month-to-Month Tenancy Termination Notice Requirements

Requirements one by one

Governing law

Colorado splits the question in two. The plain notice-to-terminate statute,
C.R.S. § 13-40-107, gives the number of days for a no-cause termination. But a
2024 law changed who may use it: § 13-40-107 now applies on the landlord side
only to nonresidential property and to the residential tenancies that are
exempt from the for-cause law, while any tenant may still use it. For
tenancies the for-cause law covers, the landlord must instead satisfy C.R.S.
§ 38-12-1303 (enacted as 2024 HB 24-1098, and renumbered from former
§ 38-12-1401 by 2025 SB 25-275, effective August 6, 2025). Nonpayment and
lease-breach evictions run under § 13-40-104 and are outside this page.

The two clocks: 21 days, or cause after a year

For an ordinary month-to-month tenancy, the no-cause figure is 21 days.
Section 13-40-107(2)(c) sets "at least twenty-one days" for "a tenancy of one
month or longer but less than six months," which is the monthly tier. A tenant
of any rental may give that 21-day notice with no reason (§ 13-40-107(1)). A
landlord may give the same 21-day no-cause notice — but only if the tenancy
is exempt from the for-cause law, most commonly because "a residential tenant
… has not been a tenant of a residential premises for at least twelve months"
(§ 38-12-1302(1)(e)). Once the tenant passes 12 months, the landlord can no
longer end the tenancy for no reason at all (see Just-cause limits).

When termination takes effect

The notice must be "written notice that expires at the end of the period" and be
"served before the end of the period" (§ 13-40-107(1),(2)). For a monthly
tenancy, deliver the 21-day notice at least 21 days before the last day of a
monthly period; it then ends the tenancy at the close of that period. Serve it
too late and it does not shorten to a random date — it takes effect at the end of
the next full period. A covered no-fault eviction is different: it names a vacate
date "at least ninety days after" service (§ 38-12-1303(3)).

How notice must be delivered

Section 13-40-108 says a written notice to vacate "may be served by delivering a
copy of the notice to a known tenant occupying the premises," by leaving it with
a suitable person at the residence, or — if personal service cannot be made — by
posting it on the premises. Any "personal service or service by posting must be
made at least twenty-four hours before" the return time stated in a later
eviction summons. Use a method that fixes the delivery date, because the notice
period runs from service.

Just-cause limits

This is where Colorado departs from most states. Since 2024, "a landlord shall
not serve a notice to terminate tenancy or a demand for possession or otherwise
proceed with an action for unlawful detainer … unless there is cause for the
eviction" (§ 38-12-1303(1)). "Cause" is either a tenant violation or one of the
statutory no-fault grounds in § 38-12-1303(3) — for example, substantial
repairs that require the unit to be vacated, demolition or withdrawal of the unit
from the rental market, or occupancy by the owner or the owner's family. Each
no-fault ground requires at least 90 days' written notice.

The law does not reach every tenancy. Section 38-12-1302(1) exempts short-term
rentals, employer-provided housing, and — the exemption that matters most for
month-to-month tenants — a tenant who "has not been a tenant of a residential
premises for at least twelve months." So the practical rule is a timeline: under
12 months, a landlord can end a month-to-month tenancy with a plain 21-day
no-cause notice; at and after 12 months, the landlord needs cause or a 90-day
no-fault ground. These protections cannot be waived by the lease (§ 38-12-1305),
and a landlord who ignores them hands the tenant a defense or a claim for relief
(§§ 38-12-1304, 38-12-1306).

What trips people up

The 12-month line changes everything for a landlord. The same monthly tenancy
that a landlord could end on 21 days' no-cause notice at month 11 requires
statutory cause — or a 90-day no-fault ground — at month 12
(§§ 38-12-1302(1)(e), 38-12-1303). Count the tenant's occupancy before assuming a
no-cause notice is available.

A tenant's clock is not affected by the for-cause law. A tenant may always end
a month-to-month tenancy on 21 days' notice under § 13-40-107(1); the 90-day and
cause rules bind landlords, not tenants.

21 days is measured to the end of a period. The notice must expire at the end
of a monthly period and be served before that period ends (§ 13-40-107(1),(2)).
Counting a flat 21 days from any date, without lining it up to the period, can
leave the notice a full month short.

Common questions

I've rented month-to-month in Colorado for two years and my landlord gave me a
30-day no-cause notice. Is that valid? Generally no. After 12 months the
tenancy is covered by the for-cause law, so the landlord needs statutory cause or
a 90-day no-fault ground (§§ 38-12-1302(1)(e), 38-12-1303), not a plain no-cause
notice.

I want to move out of my month-to-month rental. How much notice do I give?
Twenty-one days' written notice, set to end at the close of a monthly period
(§ 13-40-107(2)(c)). You do not need a reason.

My landlord says a "no-fault" eviction still lets them make me leave — is that
right? Only on a specific statutory ground (such as major repairs, taking the
unit off the market, or owner move-in) and only with at least 90 days' written
notice (§ 38-12-1303(3)).

Statutes and sources

• C.R.S. § 13-40-107 — notice to terminate tenancy: who may give a no-cause
  notice (1), the day tiers including 21 days for a month-to-month tenancy
  (2)(c), required contents (3), and no tenant notice for a fixed term ending at
  a time certain (4).
  https://olls.info/crs/crs2025-title-13.htm (accessed 2026-07-15)
• C.R.S. § 13-40-108 — service of the notice to vacate: personal delivery,
  leaving with a suitable person, or posting.
  https://olls.info/crs/crs2025-title-13.htm (accessed 2026-07-15)
• C.R.S. § 38-12-1302 — applicability of the for-cause law and its exemptions,
  including the under-12-month tenant carve-out (1)(e).
  https://olls.info/crs/crs2025-title-38.htm (accessed 2026-07-15)
• C.R.S. § 38-12-1303 — cause required for eviction; the no-fault grounds and the
  90-day written-notice requirement (3).
  https://olls.info/crs/crs2025-title-38.htm (accessed 2026-07-15)
• C.R.S. § 38-12-1305 — no waiver of the for-cause requirements by agreement.
  https://olls.info/crs/crs2025-title-38.htm (accessed 2026-07-15)