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 Virginia, the written lease agreement is indeed a crucial document outlining the rights and responsibilities of both the residential tenant and the landlord. Virginia law requires that the terms of the lease, including the conditions under which late fees may be imposed, be clearly stated in the written lease agreement. According to the Virginia Residential Landlord and Tenant Act, landlords are allowed to charge late fees, but these fees must not exceed the lesser of 10% of the periodic rent or 10% of the remaining balance due. Additionally, the lease must specify when rent is due, and late fees can only be charged after rent is five days late, unless the lease specifies a different period. The concept of an implied duty of good faith and fair dealing is recognized in Virginia contract law, which means that a landlord's actions in charging late fees should be reasonable and not violate this duty. For instance, charging a late fee for rent that is only an hour late without a specific provision in the lease stating such a strict deadline could potentially be seen as a breach of good faith and fair dealing. Tenants should read their lease agreements carefully and may seek the advice of an attorney if they believe their landlord is not adhering to the terms of the lease or Virginia law.