Depends on what was written in the deposit item of the lease.

Some localities may prohibit the use of deposit to offset unpaid rent. Not where I am.

So many times my tenants said: "You can not keep my deposit." My lawyer then said:"Are you a lawyer? Who told you this? Which law school did he graduated from? Tell me which line in the law said the landlord can not keep the deposit for unpaid rent?" Then they just shutted up.