Client billing

Invoice reminder

Send a polite reminder with the amount due, the deadline, and how to pay.

File types: PDF
Size: A4 PDF
Use case: Client billing
Licence: Free to copy and use in your own templates
Source: Made by thirds.ai with the open-licence Anton font, original graphic marks, and fictional sample names.

A portrait A4 payment reminder with a dark navy header for Northline Studio, an orange Payment due tag dated 2026-10-15, the large navy amount $1,240.00, a tan note band, and a white How to pay box. — invoice-reminder/template.html

About this design

What you can make with it.

Freelancers and small teams send this when a client's payment is late. It shows the invoice number, the due date, the amount owed, and a short note on how and where to pay. Replace the client, amount, and due date for every reminder you send.

Your details

What you can change.

These are the words and numbers you swap for your own. The design stays the same.

Business nameA short text.
Business emailA short text.
Client nameA short text.
Client emailA short text.
Invoice numberA short text.
Issued onA short text.
Due onA short text.
Amount dueA number.
Currency labelA short text.
Payment termsA short text.
Reminder messageA longer text with more than one line.
Payment noteA longer text with more than one line.
FooterA short text.

{
  "business_name": "Northline Studio",
  "business_email": "accounts@northlinestudio.co.uk",
  "client_name": "Fieldnote Labs",
  "client_email": "finance@fieldnotelabs.co.uk",
  "invoice_number": "INV-2026-091",
  "issued_on": "2026-10-01",
  "due_on": "2026-10-15",
  "amount_due": 1240,
  "currency_label": "USD",
  "payment_terms": "Payment is due within 14 days of the invoice date shown above.",
  "reminder_message": "A friendly reminder that invoice INV-2026-091 is due on 15 October 2026. Please let us know if your payment is already on its way, and get in touch if you have any questions about this invoice.",
  "payment_note": "Please use the invoice number as your payment reference. Email accounts@northlinestudio.co.uk if you need a copy of the original invoice.",
  "footer": "Northline Studio Ltd. Company no. 10294857. VAT registration GB 298 4471 05."
}

For developers

Make this file from your code or your AI tools.

Save your copy once, then send the new details with each request. Each finished file costs 1 credit.

curl https://thirds.ai/v1/pdf \
  -H "Authorization: Bearer $THIRDS_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: invoice-reminder-1" \
  -d '{"template_id":"tpl_your_copy","version":1,"data":{"business_name":"Northline Studio","business_email":"accounts@northlinestudio.co.uk","client_name":"Fieldnote Labs","client_email":"finance@fieldnotelabs.co.uk","invoice_number":"INV-2026-091","issued_on":"2026-10-01","due_on":"2026-10-15","amount_due":1240,"currency_label":"USD","payment_terms":"Payment is due within 14 days of the invoice date shown above.","reminder_message":"A friendly reminder that invoice INV-2026-091 is due on 15 October 2026. Please let us know if your payment is already on its way, and get in touch if you have any questions about this invoice.","payment_note":"Please use the invoice number as your payment reference. Email accounts@northlinestudio.co.uk if you need a copy of the original invoice.","footer":"Northline Studio Ltd. Company no. 10294857. VAT registration GB 298 4471 05."}}'

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "render",
    "arguments": {
      "output": "pdf",
      "idempotency_key": "invoice-reminder-1",
      "request": {
        "template_id": "tpl_your_copy",
        "version": 1,
        "data": {
          "business_name": "Northline Studio",
          "business_email": "accounts@northlinestudio.co.uk",
          "client_name": "Fieldnote Labs",
          "client_email": "finance@fieldnotelabs.co.uk",
          "invoice_number": "INV-2026-091",
          "issued_on": "2026-10-01",
          "due_on": "2026-10-15",
          "amount_due": 1240,
          "currency_label": "USD",
          "payment_terms": "Payment is due within 14 days of the invoice date shown above.",
          "reminder_message": "A friendly reminder that invoice INV-2026-091 is due on 15 October 2026. Please let us know if your payment is already on its way, and get in touch if you have any questions about this invoice.",
          "payment_note": "Please use the invoice number as your payment reference. Email accounts@northlinestudio.co.uk if you need a copy of the original invoice.",
          "footer": "Northline Studio Ltd. Company no. 10294857. VAT registration GB 298 4471 05."
        }
      }
    }
  }
}