How Much for Lease Breaking Fee

[Matt Faix]

We have a tenant that want's to break their lease and in our lease it states that they owe one month rent as a penalty. However, for this property the utilities are included, so the rent as single amount. This tenant is asking if the fee will be the full rent amount which includes the utilities or a lower base amount.    Since this base amount isn't really defined, would you charge the rental amount that is actually in the lease, or subtract what the average utilities might be and come up with a number? Thanks for any suggestions.