Title XXIX Chapter 441 Landlord and Tenant of Missouri Revisor of Statutes governs month-to-month leases in Missouri. State law limits the security deposit amount charged by landlords to no more than two months’ rent. The landlord must return the security deposit along with an itemized list of deductions to the tenant within 30 days of moving out. The landlord may keep some or all of the security deposit for damage to the rental unit that exceeds normal wear and tear, nonpayment of rent, or rent that the landlord lost because of inadequate notice of lease termination.
Under §441.060, the notice period for a lease termination of a month-to-month lease is 30 days. The state law specifically mentions that it must be a written notice.