ORS § 90 § 90.412

(1) As used in this section and ORS 90.414 and 90.417, “rent” does not include funds paid to a landlord:

(a) Under the United States Housing Act of 1937 (42 U.S.C. 1437f).

(b) By any other local, state or federal housing assistance program.

(2) Except as otherwise provided in this section, a landlord waives the right to terminate a rental agreement for a particular violation of the rental agreement or of law if the landlord:

(a) During three or more separate rental periods, accepts rent with knowledge of the violation by the tenant; or

(b) Accepts performance by a tenant that varies from the terms of the rental agreement.

(3) A landlord has not accepted rent for purposes of subsection (2) of this section if:

(a) Within 10 days after receipt of the rent payment, the landlord refunds the rent; or

(b) The rent payment is made in the form of a check that is dishonored.

(4) A landlord does not waive the right to terminate a rental agreement for a violation under any of the following circumstances:

(a) The landlord and tenant agree otherwise after the violation has occurred.

(b) The violation concerns the tenant’s conduct and, following the violation but prior to acceptance of rent for three rental periods or performance as described in subsection (2) of this section, the landlord gives a written warning notice to the tenant regarding the violation that:

(A) Describes specifically the conduct that constitutes the violation, either as a separate and distinct violation, a series or group of violations or a continuous or ongoing violation;

(B) States that the tenant is required to discontinue the conduct or correct the violation; and

(C) States that a reoccurrence of the conduct that constitutes a violation may result in a termination of the tenancy pursuant to ORS 90.392, 90.398, 90.405 or 90.630.

(c) The violation concerns the tenant’s failure to pay money owed to the landlord for damage to the premises, damage to any other structure located upon the grounds, utility charges, fees or deposits and, following the violation but prior to the acceptance of rent for three rental periods or performance as described in subsection (2) of this section, the landlord gives a written warning notice to the tenant regarding the violation that:

(A) Describes specifically the basis of the claim and the amount of money owed that constitutes the violation;

(B) States that the tenant is required to correct the violation by paying the money owed; and

(C) States that continued nonpayment of the money owed that constitutes a violation may result in a termination of the tenancy pursuant to ORS 90.392.

(d) The tenancy consists of rented space for a manufactured dwelling or floating home as described in ORS 90.505, and the violation concerns:

(A) Disrepair or deterioration of the manufactured dwelling or floating home pursuant to ORS 90.632; or

(B) A failure to maintain the rented space, as provided by ORS 90.740 (2), (4)(b) and (4)(h) and (i).

(e) The termination is under ORS 90.396.

(f) The landlord accepts:

(A) A last month’s rent deposit collected at the beginning of the tenancy, regardless of whether the deposit covers a period beyond a termination date;

(B) Rent distributed pursuant to a court order releasing money paid into court as provided by ORS 90.370 (1); or

(C) Rent paid for a rent obligation not yet due and paid more than one rental period in advance.

(5)(a) For a continuous or ongoing violation, the landlord’s written warning notice under subsection (4)(b) of this section remains effective for 12 months and may be renewed with a new warning notice before the end of the 12 months.

(b) For a violation concerning the tenant’s failure to pay money owed to the landlord, the landlord’s written warning notice under subsection (4)(c) of this section remains effective for 12 months from the date of the tenant’s failure to pay the money owed.

(6) A landlord that must refund rent under this section or ORS 90.414 shall make the refund:

(a) To the tenant by personal delivery or first class mail in any form of check or money or electronically as provided in ORS 90.300 (13); or

(b) To any other payer by personal delivery or first class mail in any form of check or money.