Subject: Invoice [INVOICE_NUMBER] - Payment Reminder

Hi [CLIENT_NAME],

I hope you're well. I wanted to follow up on invoice [INVOICE_NUMBER] for [AMOUNT], which was due on [DUE_DATE].

I understand you may have been busy, but I'd appreciate it if you could process this payment at your earliest convenience.

Payment details:
- Invoice Number: [INVOICE_NUMBER]
- Amount Due: [AMOUNT]
- Due Date: [DUE_DATE]
- Days Overdue: [DAYS_OVERDUE]

[PAYMENT_INSTRUCTIONS]

If you've already sent payment, please disregard this email. If you have any questions or concerns, please don't hesitate to reach out.

Thank you for your prompt attention to this matter.

Best regards,
[YOUR_NAME]
[YOUR_BUSINESS_NAME]
[CONTACT_EMAIL]
[CONTACT_PHONE]