Legal Question in Landlord & Tenant Law in California

An agreed to late fee is both logical and legal; there are costs to a landlord, both in time and money, when a tenant is late with their rental payment. There is some suggestion and certainly a reasonable argument that the court can consider if the amount of the fee is reasonable as related to the actual economic effect upon the landlord. That effect, of course, must be calculated in regard to the average tenant that landlord has, as a provision in the lease that the fee will be as the landlord calculates it for the particular incident would be considered too vague to enforce.

You need to remember that renting property out is a business. If you are late in paying a a bill to a merchant you are charged a fee; why should it be any different with the landlord. If the landlord can not make any money on the rental, why should they rent it out. A rental unit is not the tenant's private home, it is their rental unit which is owned by another who has certain legal and contractual duties.