Invoice email templates for sending and following up

What should an invoice email say?

An invoice email should identify the job and invoice number, state the amount due and agreed payment date, and tell the customer where to find payment instructions. Attach the invoice as a PDF and use a subject line the customer can search for later.

The three templates below cover the first send, a reminder on the due date and a follow-up after it. Replace every bracketed field. The example amount of $185.00 is fictional and matches our simple invoice example.

Before writing, check whether the customer asked for a supplier portal or a dedicated billing address. An email to your day-to-day contact may not reach the person who processes payments. Use the route you agreed when accepting the job.

Template 1: sending an invoice after a job

Subject: Invoice INV-2026-014 for [job description], due September 30, 2026

Hi [customer name],

Attached is invoice INV-2026-014 for [job description] completed on September 16, 2026. The amount due is $185.00 USD, payable by September 30, 2026 as agreed.

Payment instructions are on the invoice. Please use INV-2026-014 as the payment reference.

If you need any detail corrected or an order reference added, please reply to this email.

Thank you,
[your name]
[business name]
[contact details]

Attach INV-2026-014.pdf before you press send. Open the attachment from the draft email to confirm it is the finished invoice, not an old version or another customer's file. If you have not created the PDF yet, follow our free invoice PDF guide.

Keep the subject factual. The invoice number and job description help someone find the message; an urgent label adds little when payment is not yet due. Do not promise a payment option that the invoice does not actually support.

Template 2: a reminder when payment is due

Subject: Payment due today: invoice [number] for [job]

Hi [customer name],

A quick reminder that invoice [number] for [job] is due today, [date]. The remaining balance is [amount and currency]. I have attached the invoice again for reference.

If you have already sent payment, thank you. Please let me know the payment date and reference so I can match it to the invoice.

If anything is holding up approval, please reply and I will help resolve it.

Thank you,
[your name]

Check your payment records before using this message. If the customer paid part of the invoice, state the remaining balance rather than copying the original total. Use “due today” only on the actual agreed due date.

A reminder should reduce the customer's work. Reattach the relevant document, keep the reference consistent and give them a clear way to raise a problem. There is no need to describe the whole job again.

Template 3: following up on an unpaid invoice

Subject: Payment update requested: invoice [number]

Hi [customer name],

I am following up on invoice [number] for [job], which was due on [date]. My records show a remaining balance of [amount and currency]. A copy is attached.

Could you confirm when payment is expected? If there is a query with the invoice or it needs to go to someone else, please let me know.

If payment has already been made, please send the date and reference so I can check.

Thank you,
[your name]
[contact details]

Use this after checking the due date and payments received. Avoid guessing why the customer has not paid. A missing order number, a disputed line and a message sent to the wrong address need different responses; this wording lets the customer tell you which problem to solve.

Keep the follow-up in the original email thread where practical. It preserves the context and avoids leaving the customer with several unrelated messages about the same invoice. This template does not add interest, fees or new payment terms.

A final check for each message

Match five details across the subject, message and PDF: invoice number, customer, job, balance and due date. Then check the recipient and attachment. If payment instructions have changed, confirm the change through a contact route the customer already knows.

The UK's Small Business Commissioner invoicing guide recommends clear descriptions, purchase order references where supplied and terms agreed in advance. Those practical checks inform this checklist; the email wording above is an original example.

Invoice Koi's free browser generator creates the document. You save the PDF and send it through your own email. It does not send these reminders automatically. Keep the sent message and your saved invoice together so the next follow-up starts from a reliable record.