The tenant’s second late payment is the lease negotiating itself.

Landlords accept late rent in silence, and every silent month moves the due date a little further from the one in the lease.

It starts with relief. The lease says rent is payable in advance at the start of the month, the money arrives well into the second week, and the landlord, glad to be paid at all, says nothing. The next month it comes a few days later still. By then both sides are living by a different lease from the one they signed, and only one of them has noticed.

Most written leases try to guard against this with a clause saying that any relaxation or indulgence by the landlord does not change the terms. The clause helps on paper, but it does not change how people feel. A tenant who has paid late for months without a word of complaint will hear a sudden demand for punctual rent as unfair, and the relationship takes the strain even when the lease is on the landlord's side. A short written note acknowledging each late payment and restating the due date keeps the record clean and the terms alive. Saying nothing is also an answer.