Should I send an invoice letter with the invoice or just attach it?

Send a brief email message (2-3 sentences) along with the invoice attachment. This personalizes the request and gives context. Just attaching the invoice without a note feels cold and might get lost in their inbox. A short message says 'I'm following up on our work together' and shows professionalism.

What tone should my invoice letter have?

Professional but friendly. You're reminding them of great work you did together and asking them to pay. Avoid aggressive language. Avoid overly casual language too. Strike a balance: warm and appreciative, but clear about what you need (payment by a specific date).

Is it okay to mention payment terms in my letter or just in the invoice?

Mention the key terms in both. In your letter, mention the due date briefly. In the invoice, list full terms and payment methods. This redundancy ensures the client sees the information and doesn't miss it in the invoice document.

Invoice Letter Example: What to Say When You Send an Invoice

The email that accompanies your invoice matters. A few professional sentences can mean the difference between fast payment and a delayed check. Here’s what to say and how to say it.

Why Your Invoice Letter Matters

An invoice in someone’s inbox might get overlooked. A brief, friendly message saying “Your invoice is attached” brings it to their attention. It also creates a record of when you sent the invoice, which helps if payment is delayed.

Your letter doesn’t need to be long. Three to four sentences is perfect. You’re reminding the client of the work, referencing the invoice, stating the due date, and thanking them.

Basic Invoice Letter Template

Here’s a straightforward template you can adapt:

Hi [Client Name],

Thank you for the opportunity to work on [project name]. I’ve completed [brief description of deliverables] as discussed. Please find the invoice attached for [dollar amount]. Payment is due by [due date].

If you have any questions about the invoice or the work, feel free to reach out.

Thank you, [Your Name]

This works for any client and any project size. Fill in the brackets and you’re done. It’s professional, appreciative, and clear.

Example for Hourly Work

If you billed by the hour, adjust your message slightly:

Hi Sarah,

I’ve finished the copywriting project we discussed. I’ve completed [X hours] of work on your website homepage, blog posts, and product pages. The invoice for $[amount] is attached and is due by [date].

Please let me know if you’d like any revisions or have questions.

Best regards, [Your Name]

This tells the client exactly what they’re paying for. You listed the hours and the work type, so there’s no confusion.

Example for Project-Based Work

For fixed-price projects, the message is even simpler:

Hi [Client Name],

I’m pleased to send you the invoice for the [project name] project. As discussed, the total is $[amount], due by [date]. The deliverables were completed on [date], and you should have received them via [email/drive/etc.].

Thank you for the opportunity to work together.

Best, [Your Name]

This confirms that deliverables were already sent and payment is now expected. It’s formal but warm.

Pricing pricing strategy growth chart — Keep your invoice letter brief, professional, and friendly. 3-4 sentences is perfect.

Example for Retainer or Ongoing Clients

If you invoice the same client regularly, your message can be shorter because they know the routine:

Hi [Client Name],

Your May retainer invoice is attached ($[amount], due by [date]).

Thanks, [Your Name]

Regular clients don’t need reminders about your relationship or detailed explanations. Keep it brief.

Example for Late Payment Follow-Up

If an invoice is unpaid after the due date, send a reminder. Keep it polite and professional:

Hi [Client Name],

I wanted to follow up on invoice INV-[number] dated [date] for $[amount]. This invoice is now [X days] overdue.

Could you please confirm that you received it and when I can expect payment?

Thank you, [Your Name]

Don’t be accusatory. State facts and ask for confirmation. Most late payments are oversights, not intentional. Assume good faith.

Example for Second Reminder

If still unpaid after another week, follow up with slightly firmer language:

Hi [Client Name],

I’m writing to follow up on invoice INV-[number] for $[amount], which is now [X days] overdue (due date: [original due date]). I haven’t received payment or a response to my previous message.

Could you please prioritize this? If there’s an issue with the invoice, I’m happy to discuss it. Otherwise, I need payment by [new deadline].

Thank you, [Your Name]

This is firmer but still professional. You’re giving them a chance to explain or a new deadline. Keep records of these emails in case you need to escalate.

Best Practices for Invoice Letters

Use the client’s name. “Hi Sarah” is warmer than “To Whom It May Concern.”
Reference specific work. “Website copywriting” is better than “services.” It reminds them what they hired you for.
State the amount and due date clearly. Don’t bury these details. “Invoice for $1,500, due June 12” should be obvious.
Keep it short. Clients don’t read long emails. Three to four sentences maximum.
Be appreciative. “Thank you for the opportunity” sets a positive tone.
Provide a way to reach you. Make it easy for them to contact you with questions.
Proofread. Typos look unprofessional.

Subject Line Tips

Your subject line matters too. Good subject lines:

“Invoice INV-001: XYZ Project”
“Payment Due: Invoice #001 for [Project Name]”
“Invoice for Services Rendered (Due [Date])”

Bad subject lines:

“Invoice”
“Payment”
“Check Your Email”

A specific subject line helps clients find the email later and understand at a glance what it’s about.

When Sending to Different Contacts

If you work with one person but invoices go to accounting, send to both. Address the message to the person you worked with, but copy the accounting email:

Hi Sarah,

[Your standard message]

I’m also copying [finance person] so accounting receives the invoice for processing.

This ensures the invoice reaches the right place while maintaining your relationship with your contact.

Related: For comprehensive invoicing strategy, see how to make an invoice as a freelancer.

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