What should I write in an invoice email?

Keep it short and professional. Include a clear subject line with the invoice number, a brief message stating the amount and due date, and make sure the PDF invoice is attached. Example subject: 'Invoice #1042 from SpeakBill — Due Aug 15.'

Is it better to send an invoice as a PDF or in the email body?

Always attach a PDF. A PDF preserves formatting, looks professional, and is harder to alter than text in an email body. Most accounting software and apps export invoices as PDFs by default.

How do I follow up on an unpaid invoice sent by email?

Send a polite reminder 3-5 days before the due date, then again 1-3 days after. Keep it friendly — many unpaid invoices are simply forgotten, not refused. After two reminders, a phone call is appropriate.

July 12, 20262 min read

How to Send an Invoice by Email — Best Practices for Getting Paid.

The email that gets paid

Sending an invoice by email seems simple — attach the PDF and hit send. But how you write the email affects whether the client opens it, reads it, and pays it. A poorly written email leads to delays, confusion, and awkward follow-ups.

Subject line

The subject line should be clear and include the key details:

Good: "Invoice #1042 from SpeakBill — $450 due Aug 15"
Better: "Invoice for bathroom tile work — #1042 — due Aug 15"
Avoid: "Invoice" (too vague) or "URGENT: Please pay immediately" (creates unnecessary tension)

A good subject line tells the client exactly what the email is about before they open it. This is especially important if you are emailing a larger company where invoices go to a specific department.

Email body template

Keep the body professional but warm. Here is a template that works:

Hi [Client Name],

Thank you for the opportunity to work with you. Please find the invoice for [brief description of work] attached.

Invoice #1042 Amount: $450.00 Due Date: August 15, 2026

You can pay via [payment method]. Let me know if you have any questions.

Thanks, [Your Name] [Your Business]

This template hits every key point and takes under a minute to customize.

Attachment tips

Use PDF format — Always. PDFs look professional on any device and preserve your formatting.
Name the file clearly — Use a naming convention like Invoice-1042-SpeakBill.pdf or SpeakBill-Invoice-1042-Aug2026.pdf.
Check the file size — Keep it under 5 MB. Most invoice PDFs are under 500 KB.
Double-check the attachment — Before sending, open the PDF and verify every field.

Timing matters

Send the invoice as soon as possible after completing the work. The longer you wait, the less urgent the payment feels to the client. Research shows that invoices sent within 24 hours of work completion get paid significantly faster than those sent a week later.

Best times to send:

Tuesday through Thursday mornings — People process administrative tasks earlier in the week.
Avoid Friday afternoons — Your invoice will sit in an inbox all weekend.

Following up

Even with a great email, some clients will forget to pay. Set up a follow-up rhythm:

Reminder 1 — 3 days before the due date: "Just a quick reminder that Invoice #1042 for $450 is due on August 15."
Reminder 2 — 3 days after the due date: "Following up on Invoice #1042. Please let me know if you have any questions or need anything from my side."
Reminder 3 — 7 days after due date: A phone call is more effective than email at this point.

Always stay polite. Most late payments are accidents, not malice. A friendly tone preserves the client relationship while still getting you paid.

Subject line

The subject line should be clear and include the key details:

Good: "Invoice #1042 from SpeakBill — $450 due Aug 15"

Better: "Invoice for bathroom tile work — #1042 — due Aug 15"

Avoid: "Invoice" (too vague) or "URGENT: Please pay immediately" (creates unnecessary tension)

A good subject line tells the client exactly what the email is about before they open it. This is especially important if you are emailing a larger company where invoices go to a specific department.

Email body template

Keep the body professional but warm. Here is a template that works:

Hi [Client Name],

Thank you for the opportunity to work with you. Please find the invoice for [brief description of work] attached.

Invoice #1042 Amount: $450.00 Due Date: August 15, 2026

You can pay via [payment method]. Let me know if you have any questions.

Thanks, [Your Name] [Your Business]

This template hits every key point and takes under a minute to customize.

Attachment tips

Use PDF format — Always. PDFs look professional on any device and preserve your formatting.

Name the file clearly — Use a naming convention like Invoice-1042-SpeakBill.pdf or SpeakBill-Invoice-1042-Aug2026.pdf.

Check the file size — Keep it under 5 MB. Most invoice PDFs are under 500 KB.

Double-check the attachment — Before sending, open the PDF and verify every field.

Timing matters

Best times to send:

Tuesday through Thursday mornings — People process administrative tasks earlier in the week.

Avoid Friday afternoons — Your invoice will sit in an inbox all weekend.

Following up

Even with a great email, some clients will forget to pay. Set up a follow-up rhythm:

Reminder 1 — 3 days before the due date: "Just a quick reminder that Invoice #1042 for $450 is due on August 15."

Reminder 2 — 3 days after the due date: "Following up on Invoice #1042. Please let me know if you have any questions or need anything from my side."

Reminder 3 — 7 days after due date: A phone call is more effective than email at this point.

Always stay polite. Most late payments are accidents, not malice. A friendly tone preserves the client relationship while still getting you paid.