They must attempt to re-lease to "mitigate" their damages.
If the unit is full, they need to deduct the income from that from the amount you owe--but keep in mind, the amount you owe includes their costs in re-leasing--cleaning, search, etc.
However, if they still have empty units in the apartment that could have been rented, you may still be on the hook. They can't collect more in total breach payments than units (e.g., they can't charge 5 breached leases in full with only three empty apartments).
I've also found that most people in this situation are on the down ward slide towards bankruptcy; you should evaluate your total finances at this time, and see if your attempts to pay things are only postponing the inevitable.
You can generate a mathematical equation:
(Lease liability) - (rent payments during term from other party) = (Actual liability to landlord)
The only period you would be liable for is when the unit was empty during the term of your lease. Also, the landlord has a duty to try to rent out the unit. They cannot simply let the unit sit empty and try to collect the rent from you.
I agree with Mr. Hawkins. Your liability will be calculated based on the total number of vacant units as well as the rent received from a new tenant. Many people wait longer than they should before consulting a bankruptcy lawyer and lose assets that would otherwise be protected from creditors in a bankruptcy. I encourage you to consult with a bankruptcy attorney if you are struggling to pay your current obligations. Waiting may put you in a worse position after a bankruptcy.
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