When a tenant is ready to move out, he should give the landlord a written notice of intent to vacate, as stated by FindLaw. The letter should include the date, the renter's name and address, the landlord's name and address and the amount of the security deposit that the tenant expects to receive.
Depending on the terms of the tenant's lease, if he leaves before the lease is up, he may have to pay rent until the landlord finds another renter. If the former tenant believes that the landlord is not making a valid effort to find a new renter, a notice of duty to mitigate may be written, as reported by Nolo. This letter reminds the landlord of his legal duty to make every effort to attempt to find a new tenant.