Writing an invoice email might feel routine, but it’s actually a major part of ensuring that your work with clients goes smoothly and that you’re paid on time. A good invoice email can minimize back-and-forth and payment delays and keep your business on track.

Below are some practical tips for crafting a helpful invoice email, from outlining payment instructions to sending escalating reminders if the invoice goes unpaid.

What’s in this article?

• How to write a clear and professional invoice subject line
  
• What to include in an invoice email
  
• How to include payment links and instructions in your email
  
• When and how to follow up on unpaid invoices with email
  

How to write a clear and professional invoice subject line

Your invoice subject line should tell the recipient exactly what to expect when they open the email. A simple subject line such as “Invoice #12345 for [Your Business Name]” or “Invoice for [Project Name] – Due [Due Date]” does the job. Include the invoice number, a brief description, and a due date to make it easier for the recipient to locate and process the invoice. Including a due date can be especially helpful for ongoing work or recurring invoices, and it also gives clients a nudge to process the invoice before the deadline.

Here are some more tips for how to write the subject line:

• Subject lines that are too long often get cut off, particularly on mobile. Mention only necessary details so the recipient can get all the information at a glance.

• If you’re working with a new client or a larger company, include your business name in the subject line to help the recipient quickly identify who sent the invoice.

• While it’s tempting to add phrases such as “friendly reminder” and “just a heads-up,” these are best saved for follow-up emails if the invoice becomes overdue.

What to include in an invoice email

In your invoice email, you should provide the client with all the information they need to process payment. Provide a short summary of the invoice and payment instructions so the client knows exactly how to proceed. Here are all the details to include.

A polite greeting and thank-you

Start off with a simple, friendly greeting such as, “Hi [Client’s Name],” and consider thanking them for their business. A little courtesy goes a long way in creating a positive interaction, especially when you discuss payments.

Invoice details and purpose

Briefly mention what the invoice is for. This gives the client a heads-up and reminds them of the specific project or service.

• Example: “Please find attached Invoice #12345 for [Service or Product Provided].”
  

Invoice summary

Summarize a few key details in the body of the email, such as the invoice number, invoice date, total amount due, and due date. Outlining these details in the email itself allows the client to see everything they need to know without opening the attachment.

Payment instructions

Include instructions on how to pay and a payment link, if applicable, directly in the email. Whether the client is paying via bank transfer, credit card, or another payment method, provide them with clear steps for completing payment.

Contact information

Let clients know how to contact you if they have questions or need clarification.

• Example: “Please feel free to contact us if you need any further details or clarification.”
  

Invoice file

Don’t forget the attachment. Ensure it’s labeled so it’s easily identifiable.

• Example: “Invoice-12345-YourBusinessName.pdf”
  

A friendly closing

End your message with a simple closing such as “thanks again” or “best regards.” This keeps the tone friendly and adds a human touch to a transactional email.

How to include payment links and instructions in your email

Including payment links and instructions in your email is a simple way to make the payment process as easy as possible for your client. Here’s how to incorporate them into your email.

Provide a brief payment instruction section

Insert the payment instructions after the invoice details. Explain how to pay and include any direct links or steps required.

• Example: “To complete payment, please use the following link: [Payment Link].”
  

Make the payment link stand out

Consider formatting the payment link in bold or highlighting it so it’s easy to find. If it’s a clickable URL, ensure it’s working before you send the email. If your email format allows it, you could also use a button to draw more attention to the link.

Offer alternative payment methods, if relevant

If you accept multiple payment methods, mention them briefly so the client knows their options. List any specifics they’ll need to use these methods, such as your bank details and a link to pay via credit card.

Example

We accept payments via [Bank transfer, credit card, etc.]. For bank transfers, please use the details below:

Bank name: [Your Bank]
Account Number: [Your Account Number]
Routing Number: [Your Routing Number]
Reference: Invoice #12345

Include any additional instructions

Mention any special instructions the client needs to follow (e.g., noting the invoice number with the payment) so that payment can be processed efficiently and accurately.

• Example: “If you’re paying via bank transfer, please include your Invoice Number (#12345) in the transaction notes so we can apply it to your account right away.”
  

When and how to follow up on unpaid invoices with email

Following up on unpaid invoices is a balancing act between persistence and politeness. Follow these tips to increase your chances of collecting payment:

• Maintain a factual, polite tone. Avoid sounding accusatory or impatient.

• Be consistent with your timing. Send regular, scheduled follow-ups at the same intervals each cycle.

• Make it clear that the client should contact you if they need any clarification. Sometimes clients delay payment due to questions about the invoice or confusion about how to pay.

• Attach the invoice to each follow-up. This makes it easy for the client to access it without searching through old emails.

Below is a closer look at what each follow-up email might look like.

First follow-up

Your first follow-up should be a gentle reminder, sent one to three days after the due date. This email serves as a light nudge and assumes the client might’ve simply overlooked the due date. Use a friendly tone and express that you’re just checking in.

Example

Hi [Client’s Name],

I hope you’re doing well! I wanted to touch base regarding Invoice #12345, due on [Due Date]. I understand things can get busy so this is just a quick reminder in case it slipped through the cracks.

Invoice Summary:
Total Amount Due: $500.00

Payment Link: [Insert Payment Link]

If you’ve already sent payment, please disregard this email. Otherwise, please let me know if there’s anything I can help with.

Thanks so much,
[Your Name]

Second follow-up

If there’s no response to the first reminder, contact the client again with a polite check-in one week after the first follow-up. This email should remain polite but might include an offer to discuss any potential issues or questions.

Example

Hi [Client’s Name],

I wanted to follow up on Invoice #12345. The due date was [Due Date], and I haven’t received confirmation of payment yet. If there are any issues with the payment process, please let me know. I’m here to help.

Invoice Summary:
Total Amount Due: $500.00

Payment Link: [Insert Payment Link]

Thanks again for your attention to this. Please feel free to contact me if there’s anything you’d like to discuss.

Best regards,
[Your Name]

Third follow-up

If the invoice is still unpaid, send a firm reminder two weeks after the second follow-up. In this email, you might want to reference any agreed terms regarding overdue payments, such as late fees.

Example

Hi [Client’s Name],

I’m contacting you again regarding Invoice #12345, due on [Due Date]. I understand delays can happen, so please let me know if there are any concerns about how to process the payment.

Invoice Summary:
Total Amount Due: $500.00

Payment Link: [Insert Payment Link]

Per our agreement, payments not received by [X days past due date] might incur a late fee. We hope to resolve this soon, so please let me know if you need any further information or assistance.

Thank you for your attention to this matter.

Best regards,
[Your Name]

Final follow-up

If previous attempts haven’t resulted in payment, the final email can be a formal notice that states next steps such as suspending services and escalating the issue. It’s best to send this type of notice one month or more after the due date.

Example

Hi [Client’s Name],

This is a final follow-up regarding Invoice #12345, originally due on [Due Date]. We’ve made multiple attempts to settle this invoice, but payment has not yet been received.

Invoice Summary:
Total Amount Due: $500.00

Payment Link: [Insert Payment Link]

If payment is not received by [New Deadline], we might need to [mention any specific next steps such as suspending services, assessing a late fee, and forwarding to collections]. Please let us know if there’s anything we can clarify or if you’d like to discuss this matter further.

Thank you,
[Your Name]