First reminder about unpaid invoice
[Date] [Name] [Address] Dear [Name] We write to inform you that we have not yet received payment of invoice [Number] for [Amount] due on [Date]. We realize you must have mistakenly overlooked it but ask that you give it your prompt attention now. If payment has already been sent, please disregard this letter. If you have any queries about your account, please do not hesitate to contact me. Yours Sincerely [Your Name] [Your Title]