Before the due date
Subject: Invoice [number] — due [date]

Hi [first name],

A quick reminder that invoice [number] for [work or order] is due on [date]. The outstanding amount is [amount].

You can find the invoice and agreed payment instructions here: [secure invoice link]. Please let me know if you need anything from me to arrange payment.

Thank you,
[your name]

After the due date
Subject: Checking in on invoice [number]

Hi [first name],

I’m checking in on invoice [number], which was due on [date]. Our records show [amount] outstanding.

Could you confirm whether payment has been scheduled, or whether there is a question about the invoice that we can resolve? If you have already paid, please share the payment date or reference so we can match it.

Thank you,
[your name]

Agree on the next step
Subject: Next step for invoice [number]

Hi [first name],

Following up on invoice [number] and my message on [date]. Could you let me know the expected payment date, or the right person to speak with about this invoice?

If something is preventing payment, please reply so we can discuss the next step.

Thank you,
[your name]