A month-to-month tenancy is a periodic tenancy or lease in which the tenant is given possession of the leased premises with no specific expiration date and agrees to pay the landlord on a monthly basis. A month-to-month tenancy often requires the tenant or the landlord to give the other party 30 days written notice of termination of the lease.

Both residential leases and commercial leases may be month-to-month tenancies. If a residential or commercial tenant remains in the leased premises and continues to pay rent following the expiration of a lease for a longer term, there may be a new month-to-month tenancy created and recognized by law.

In Oregon, a month-to-month tenancy is recognized for both residential and commercial properties. This type of tenancy does not have a fixed end date and continues until either the landlord or tenant provides the other with a written notice of termination. Typically, Oregon law requires a 30-day notice period for termination of a month-to-month residential tenancy. However, in certain cities like Portland, the notice period may be longer, and additional regulations may apply. For commercial leases, the notice period may vary based on the terms of the lease agreement. If a fixed-term lease expires and the tenant remains in the property without signing a new lease but continues to pay rent, a month-to-month tenancy is often presumed to have been established under Oregon law. It's important to note that specific rules can vary, and local ordinances may impose additional requirements or protections, so it's advisable to consult with an attorney for guidance on the current regulations applicable to a particular situation.