The rule in plain English
Nebraska gives 14 days from the end of the tenancy. Within them, the landlord delivers or mails the balance of the deposit and prepaid rent, with a written itemization of what was kept (Neb. Rev. Stat. 76-1416(2)).
Rent and damages from the tenant's breach can come out of it.
For a tenant who is behind on rent, the Nebraska notice is available here.
Prepare the Nebraska noticeMore for Nebraska landlords: Nebraska Eviction Notice Selector · Eviction Notice Deadline Calculator · See the Nebraska documents