We only have one building with 4 units. Most tenants pay on time. If we haven't received rent by early evening on the due date from a tenant that is normally regular, I usually make a courtesy call, just to remind them we haven't received the rent yet and remind them if they can get it to us today (we are also close and they usually drop it off), they can avoid the late fee. However, if I have a tenant who seems to be doing this too often, I will let it go until it is late and then call and remind then that the owe the rent, plus the late fee. The few times I have had to do this, they don't do it again. Once a tenant of several years was late and I forgot to call and I did waive the late fee, but I told her I was doing so just this once so she realized we were doing her a favor and waiving the late fee wasn't going to be a regular occurrance.