What if the tenant stays in the unit after a lease expires?

It is best to negotiate the new lease before the old lease expires.  If the lease expires, the landlord can require that the tenant immediately sign a new lease lease with new terms or vacate.  If a new lease is not signed, and the landlord continues to accept monthly rent, a tenancy-at-will is created and the terms of the original lease still apply except the landlord can only terminate or change the terms with a sixty (60) day notice and the tenant can only terminate with a thirty (30) day notice.