[date]

[name]
[address]

Re: [account number]

Dear [name]:

This is in regard to your past due account, number [account number]. Currently, your account has an outstanding balance of [amount owed].
Please remit this amount at your earliest opportunity.

Thank you for your assistance in this matter. If you have any questions, please contact [contact name] at [phone number].

        Sincerely,

 
        ___________________________________