Client billing

Retainer invoice

Bill a client a monthly retainer with a large amount due.

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 Space Grotesk font, original graphic marks, and fictional sample names.

A tall cream invoice with a navy masthead and a large amount due for Harbour and Reed Advisory billing Willow and Finch. — retainers-invoice/template.html

About this design

What you can make with it.

Consultants and agencies use this invoice to bill the same client every month. It runs a quiet navy layout with the amount due set large, above a table of the month's work. Update the client, line items, and totals each time you send it.

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.
ItemsA list of items. Each item has description and amount.
SubtotalA number.
TaxA number.
TotalA number.
Payment termsA short text.
Payment noteA short text.

{
  "business_name": "Harbour & Reed Advisory",
  "business_email": "accounts@harbourreed.co.uk",
  "client_name": "Willow & Finch",
  "client_email": "finance@willowandfinch.co.uk",
  "invoice_number": "HR-22610",
  "issued_on": "2026-10-01",
  "items": [
    {
      "description": "October retained counsel, 12 hours",
      "amount": 1800
    },
    {
      "description": "Brand voice workshop, half day",
      "amount": 640
    },
    {
      "description": "Monthly report and board pack",
      "amount": 280
    },
    {
      "description": "Copy review for the autumn catalogue",
      "amount": 190
    },
    {
      "description": "Press note for the Bristol shop",
      "amount": 160
    },
    {
      "description": "Two extra review calls",
      "amount": 220
    },
    {
      "description": "Travel to the Bath studio",
      "amount": 74
    }
  ],
  "subtotal": 3364,
  "tax": 672.8,
  "total": 4036.8,
  "payment_terms": "Due within 14 days. Amounts are shown in pounds sterling.",
  "payment_note": "Please use HR-22610 as your payment reference."
}

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: retainers-invoice-1" \
  -d '{"template_id":"tpl_your_copy","version":1,"data":{"business_name":"Harbour & Reed Advisory","business_email":"accounts@harbourreed.co.uk","client_name":"Willow & Finch","client_email":"finance@willowandfinch.co.uk","invoice_number":"HR-22610","issued_on":"2026-10-01","items":[{"description":"October retained counsel, 12 hours","amount":1800},{"description":"Brand voice workshop, half day","amount":640},{"description":"Monthly report and board pack","amount":280},{"description":"Copy review for the autumn catalogue","amount":190},{"description":"Press note for the Bristol shop","amount":160},{"description":"Two extra review calls","amount":220},{"description":"Travel to the Bath studio","amount":74}],"subtotal":3364,"tax":672.8,"total":4036.8,"payment_terms":"Due within 14 days. Amounts are shown in pounds sterling.","payment_note":"Please use HR-22610 as your payment reference."}}'

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "render",
    "arguments": {
      "output": "pdf",
      "idempotency_key": "retainers-invoice-1",
      "request": {
        "template_id": "tpl_your_copy",
        "version": 1,
        "data": {
          "business_name": "Harbour & Reed Advisory",
          "business_email": "accounts@harbourreed.co.uk",
          "client_name": "Willow & Finch",
          "client_email": "finance@willowandfinch.co.uk",
          "invoice_number": "HR-22610",
          "issued_on": "2026-10-01",
          "items": [
            {
              "description": "October retained counsel, 12 hours",
              "amount": 1800
            },
            {
              "description": "Brand voice workshop, half day",
              "amount": 640
            },
            {
              "description": "Monthly report and board pack",
              "amount": 280
            },
            {
              "description": "Copy review for the autumn catalogue",
              "amount": 190
            },
            {
              "description": "Press note for the Bristol shop",
              "amount": 160
            },
            {
              "description": "Two extra review calls",
              "amount": 220
            },
            {
              "description": "Travel to the Bath studio",
              "amount": 74
            }
          ],
          "subtotal": 3364,
          "tax": 672.8,
          "total": 4036.8,
          "payment_terms": "Due within 14 days. Amounts are shown in pounds sterling.",
          "payment_note": "Please use HR-22610 as your payment reference."
        }
      }
    }
  }
}