A recent Illinois appellate court decision has actually ruled that a landlord’s 5 day notice is defective if the deadline in the notice (the 5th day) falls on a Sunday. As most landlords are aware, it must serve its non-paying tenant with a written notice before it can file an eviction lawsuit. In the residential context, and unless the lease provides for a longer time period, the notice for the non-payment of rent is 5 days, and the notice for some other default under the lease is 10 days.