Dear Mr [Last Name],
I am writing to ask you to allow late payment of my rent this month.
As you know, I have been your tenant for more than 3 years now, and I have always paid my rent on time, i.e. before 7th in the month. However, since I was dismissed from my work last Tuesday, I am having some financial issues at the moment. As I have been newbie in the company, I am not entitled to receive redundancy payment, and currently I struggle to arrange my finances for this month.
On the other hand I expect to receive the fee as a result of consultancy contract with local University by the 15th of [month] which will cover my monthly expenses. Therefore I can assure you that I will be able to pay the rent, within next few weeks. Nevertheless, I have found new part time job, which would ensure my income in the months that follow, so I will be able to continue with paying rent.
I strongly believe you will accept my sincere apologies, and will accept my request. If there is some problem do not hesitate to write or call.