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 Kansas, the written lease agreement is indeed a crucial document for outlining the rights of residential tenants and the responsibilities of landlords. Kansas law favors written leases for clarity and enforceability. Tenants should thoroughly review and understand the lease before signing, as it will detail the terms of the tenancy, including rent payments, maintenance obligations, and other important conditions. Regarding late fees, Kansas statutes do not specify a limit on the amount a landlord can charge, but the fees must be reasonable and related to the actual costs incurred by the landlord due to the late payment. The lease should clearly state the amount of the late fee, when it is assessed, and any grace period that is provided. Under Kansas contract law, there is an implied duty of good faith and fair dealing in the execution of contracts, which applies to lease agreements as well. A landlord charging excessive late fees or fees for marginally late payments could potentially be seen as acting in bad faith, especially if the lease does not explicitly define such strict terms. It is always advisable for tenants to seek clarification on any lease terms they do not understand and, if necessary, consult with an attorney for legal advice specific to their situation.