[Your letterhead, if desired; if not, your return address]
[Date of letter—month, day, and year]
[Recipient's first and last names]
[Company name]
[Street or P.O. box address]
[City, State ZIP code]
Dear [recipient's name]:
I am writing to follow up on our telephone conversation this morning regarding the payment for the $300 that I owe you. Per our conversation, I agree to pay you $150 of the total amount owed this month and $150 of the total amount owed next month. I also understand that you will not be charging me interest on the amount that I owe you. I will be paying you by mailing a check to you for each of the two payments.
Thank you for working with me to make this agreement. I truly appreciate the loan, as well as your flexibility regarding the payment arrangements. Please let me know if you have questions or need to discuss this further.
Sincerely,
[Signature]
[Sender's first and last names]