A business that leases real estate and improvements (buildings, etc.) in the form of space for offices, a warehouse, a restaurant, a nail or hair salon, a clothing store, a coffee shop, or other commercial (nonresidential) space will usually be required to sign a written contract known as a commercial lease agreement.

If the tenant (the business occupying the space) who signs a commercial lease agreement fails to pay the rent on time, the landlord may have the right to charge late fees, terminate the lease, and lock the commercial tenant out of the space by changing the locks.

A commercial landlord’s ability to charge late fees generally depends on the specific language in the written lease agreement 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 commercial 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 Montana, a business leasing commercial space such as offices, warehouses, or retail locations will typically enter into a commercial lease agreement. This legally binding contract outlines the terms and conditions of the lease, including rent payments, the duration of the lease, and the rights and responsibilities of both the landlord and the tenant. If a tenant fails to pay rent on time, the landlord's right to impose late fees, terminate the lease, or lock out the tenant will depend on the provisions of the lease agreement itself. Montana law requires that the terms of the lease be followed, and any late fee must be reasonable and agreed upon in the lease. Additionally, Montana recognizes the implied covenant of good faith and fair dealing in contracts, which means both parties are expected to act in a fair manner that does not destroy the right of the other party to receive the benefits of the contract. A landlord charging excessive late fees or acting in a manner that is overly punitive may be seen as violating this implied duty. It is important for both landlords and tenants to understand their rights and obligations under the lease agreement and Montana law.