Invoicing is one of those tasks that seems like it should be automatic once you’ve done it a few times — and mostly it is. The problems show up when something in the process is missing: the wrong email address, no payment link, a due date the client never calculated, a follow-up that came too late.
Before you send: get these two things right
1. The correct billing contact The person you’ve been working with on the project is not always the person who processes invoices. Ask before the project ends: “When we’re ready to wrap up, should I send the invoice to you or to a billing contact?” This single question prevents the most common reason invoices get delayed.
2. The exact invoice amount If there were scope changes, additions, or out-of-scope work during the project, confirm those additions with the client before the invoice arrives. Surprise charges are the second most common reason invoices get disputed.
What to include on the invoice
Required:
- Your name, business name, email, and phone
- Client’s full name, company, and billing address
- Invoice number (unique, sequential — start at 1001)
- Invoice date (the date you’re sending it)
- Payment due date (a specific calendar date, not “Net 30” alone)
- Line items: service description, quantity or hours, rate, and line total
- Total amount due (make it prominent)
- Payment instructions
Optional but useful:
- Your logo
- A project reference name or number
- Late fee terms
- Notes or a personal thank-you line
How to write the line items
The service description on each line should be specific enough that the client knows exactly what they’re paying for. Compare:
Vague: Consulting services — $2,000 Clear: Brand positioning workshop (3 hours) + written strategy brief — $2,000
The second version answers the question “what did I get for this?” without requiring a conversation. Clear line items reduce invoice disputes and speed up approval.
If the project had additional work beyond the original scope: “Additional revision round (3rd round, approved via email May 20): $200”
Note the approval — it signals you’re referencing a specific conversation, not adding charges arbitrarily.
How to send the invoice
Email is the standard. Attach the invoice as a PDF. In the body of the email, include:
- The invoice number and project name
- The total amount
- The due date
- The payment link or payment instructions
Don’t make the client open the PDF to find the total — put it in the email. Clients who see the amount and a payment link immediately can pay in 30 seconds without opening an attachment.
Sample sending email:
Hi Sarah,
Please find Invoice #1042 for the Bright Leaf brand identity project attached — total $2,800, due June 10.
Pay online here: [payment link]
Let me know if you have any questions about the line items.
Thanks, Marcus
That email does the job. No lengthy explanation, no excessive politeness, no padding.
The payment link in the email body — not just in the PDF — is the single highest-impact change you can make to your invoicing process. Reducing the steps between “client reads the email” and “client pays” directly speeds up payment.
After you send: know whether it was received
One of the most useful pieces of information you can have after sending an invoice is whether the client has actually seen it. If the due date passes and you don’t know whether the invoice was opened, your follow-up has to be cautious (“just checking if you received this”) rather than direct (“I saw you opened this, is there a hold-up?”).
Waco3 records when a client opens your invoice, including the time and device, so you can follow up appropriately. A client who’s opened the invoice three times and hasn’t paid needs a different message than a client whose invoice has never been opened.
Following up on unpaid invoices
Send your first follow-up the day after the due date, not a week later. Most invoices that go overdue aren’t intentional — they’re overlooked.
Day after due date:
Hi Sarah, just flagging that Invoice #1042 for $2,800 was due yesterday. Please let me know if there’s anything preventing payment or if you need me to send it to a different contact. [Payment link]
One week overdue:
Hi Sarah, following up again on Invoice #1042 ($2,800, due June 10). I haven’t received payment yet — please let me know by Friday if there’s an issue I should know about. [Payment link]
30+ days overdue: At this point, the tone becomes firmer, you reference your payment terms explicitly, and you name a consequence if payment doesn’t arrive by a specific date.
The majority of invoices are paid before reaching the 30-day mark. Prompt, professional follow-up is what makes the difference.
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