Email subject: Payment for invoice #_ is one week overdue
According to my records, I have yet to receive payment in the amount of _ for the invoice #_ sent on _, which is now one week overdue. Attached is the copy of the invoice with the amount due, for your convenience.
If you have any questions about the payment, please let me know. I’m also attaching a copy of the invoice in case you did not receive the original, for whatever reason.
Could you please reply to this email to let me know you have received it? Thank you!
One month after the payment due date
Email subject: Payment for invoice #_ is one month overdue
This is another reminder that you have yet to pay invoice #_ for the amount of _to my bank account. Please be aware that, according to the terms of my business, I may ask for an additional fee to be paid for all invoices that are more than 30 days past their payment date.