The most important source of information about a residential tenant’s rights and a landlord’s responsibilities is the written lease agreement. Some landlords prefer oral agreements, but it is more common for them to require the tenant's signature on a written lease—and a written lease protects the tenant more than an oral agreement. Be sure to read the lease carefully before you sign it.

A residential landlord’s ability to charge late fees generally depends on the specific language in the written lease agreement; the state’s landlord-tenant laws that may limit the amount of late fees the landlord can charge and the circumstances in which they can be charged; and the state's contract law.

Contract law in most states recognizes an implied duty of good faith and fair dealing between parties to a contract, and a residential landlord who charges late fees because the tenant is an hour late paying the rent may be in breach of the landlord’s implied duty of good faith and fair dealing—unless, for example, the lease agreement specifies an hour (12:00 p.m.) of the day by which rent is due and states that time is of the essence.

In Oregon, the written lease agreement is indeed a crucial document outlining the rights and responsibilities of both the residential tenant and the landlord. It is advisable for tenants to thoroughly review and understand the lease before signing, as it provides more legal protection than an oral agreement. Regarding late fees, Oregon's landlord-tenant laws stipulate that any late fees must be outlined in the written lease agreement and are subject to limitations. Specifically, ORS 90.260 limits late fees to reasonable amounts and requires that rent must be at least four days late before a late fee can be charged. Additionally, Oregon law embodies the principle of an implied duty of good faith and fair dealing in contractual relationships, which means that a landlord's actions, including the imposition of late fees, should be fair and not punitive in nature. A landlord charging a late fee for rent that is only an hour late could potentially be seen as acting in bad faith, especially if the lease does not explicitly state such stringent time requirements. It is important for tenants to be aware of these protections and for landlords to ensure their lease agreements and practices comply with Oregon statutes and the principles of contract law.