It is easy for landlords and tenants to end a month-to-month tenancy in Oregon. (The situation is more complicated when it comes to breaking a fixed-term lease.)
In most situations your landlord does not need to give you a reason (although acting on discriminatory or retaliatory motives is illegal) to end a month-to-month tenancy. A landlord can simply give you a written notice to move, allowing you 30 days (for occupancies of one year or less) or 60 days (for occupancies of more than one year, but only 30 days if the property is sold and other conditions are met) as required by Oregon law. Temporary occupants are not entitled to notice.
Your landlord may legally provide less less notice in specific circumstances--for example, if you have not paid rent, if you have violated other terms of your rental agreement (for example, bringing in an unauthorized tenant), or if you have violated basic responsibilities imposed by law (such as by dealing drugs on the rental property).
Oregon tenants who want to get out of a month-to-month rental agreement must provide 30 days’ notice (unless your reason for moving is lack of a bedroom exit, in which case only 72 hours' notice is required). Be sure to check your rental agreement which may require that your notice to end the tenancy be given on the first of the month or on another specific date, or may provide for a shorter amount of notice.
In some situations, you may be able to move out with less (or no) notice—for example, if your landlord seriously violates the rental agreement or fails to fulfill legal responsibilities affecting your health or safety.
Check Oregon state law (Ore. Rev. Stat. §§ 91.070, 90.427, 90.275, 90.460) for the exact rules and procedures for how landlords must prepare and serve termination notices and for any special rules regarding how tenants must provide notice. See the Laws and Legal Research section of Nolo for advice on finding and reading statutes and court decisions.