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 Connecticut, 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 may impose late fees, terminate the lease, or even lock the tenant out of the premises, depending on the provisions of the lease agreement. Connecticut law requires that the terms of the lease, including the imposition of late fees, adhere to the principle of good faith and fair dealing. This means that a landlord's actions, such as charging late fees for minor delays in rent payment, must be reasonable and not violate the spirit of the agreement. If the lease specifies a precise time for rent payment and declares that time is of the essence, the landlord may have firmer grounds to enforce such provisions. However, any enforcement action by the landlord, including lockouts, should be conducted in accordance with Connecticut's laws and the specific terms of the lease agreement.