curl -X PATCH https://invoice.horizonpay.co/api/v1/invoices/in_Pb2Xk7Mv4Qs9Lr1Wd6Tn3Fh8 \
  -H "Authorization: Bearer $INVOICE_AI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "due_date": "2026-10-22",
    "description": "Consulting retainer — net 30.",
    "footer": "Thank you for your business."
  }'

import InvoiceAI from '@horizonpay/invoice-ai'

const invoiceai = new InvoiceAI() // reads INVOICE_AI_API_KEY

const invoice = await invoiceai.invoices.update('in_Pb2Xk7Mv4Qs9Lr1Wd6Tn3Fh8', {
  due_date: '2026-10-22',
  description: 'Consulting retainer — net 30.',
  footer: 'Thank you for your business.',
})
console.log(invoice.due_date, invoice.total)

from invoice_ai import InvoiceAI

client = InvoiceAI()  # reads INVOICE_AI_API_KEY

invoice = client.invoices.update(
    "in_Pb2Xk7Mv4Qs9Lr1Wd6Tn3Fh8",
    due_date="2026-10-22",
    description="Consulting retainer — net 30.",
    footer="Thank you for your business.",
)
print(invoice.due_date, invoice.total)

{
  "data": {
    "id": "in_Pb2Xk7Mv4Qs9Lr1Wd6Tn3Fh8",
    "object": "invoice",
    "number": null,
    "status": "draft",
    "customer": "cus_Nf3kQ8pR2mX7vB1cT9wL4sZ6",
    "currency": "USD",
    "collection_method": "send_invoice",
    "issue_date": "2026-09-22",
    "due_date": "2026-10-22",
    "description": "Consulting retainer — net 30.",
    "footer": "Thank you for your business.",
    "subtotal": 2550000,
    "discount": 0,
    "taxable": 2550000,
    "tax": 0,
    "total": 2550000,
    "amount_due": 0,
    "amount_in_words": "Twenty Five Thousand Five Hundred USD Only",
    "public_url_token": "2b7e4c1a-9f3d-4e68-8a5b-0d1c7f3e9a46",
    "finalized_at": null,
    "paid_at": null,
    "voided_at": null,
    "void_reason": null,
    "created": "2026-09-22T09:30:00.000Z",
    "updated": "2026-09-22T09:45:00.000Z",
    "lines": {
      "data": [
        {
          "id": "ii_Da4Vq9Ns2Kx7Bm3Yt8Rc1Lp6",
          "object": "invoiceitem",
          "price": "price_Jc5Tn8Wq1Ze6Ra3Ym9Ub2Gs7",
          "product": "prod_Hy7Rq2Lm9Xc4Vb8Nt3Kd6Pw1",
          "description": "Consulting retainer",
          "quantity": 1,
          "unit": "NOS",
          "unit_amount": 2500000,
          "amount": 2500000,
          "discount_percent": 0,
          "tax_rate": 0,
          "tax_amount": 0
        },
        {
          "id": "ii_Ew8Hz3Jc6Tq1Ms5Nv9Kb2Xr4",
          "object": "invoiceitem",
          "price": null,
          "product": null,
          "description": "Onboarding workshop",
          "quantity": 1,
          "unit": "NOS",
          "unit_amount": 50000,
          "amount": 50000,
          "discount_percent": 0,
          "tax_rate": 0,
          "tax_amount": 0
        }
      ]
    }
  }
}

{
  "type": "https://invoice.horizonpay.co/problems/unauthorized",
  "title": "Unauthorized",
  "status": 401,
  "detail": "Send your API key as `Authorization: Bearer inv_live_…`.",
  "instance": "req_7f3c9a1e2b4d4e8a9c6f2d1b0a3e5f71",
  "code": "unauthorized"
}

{
  "type": "https://invoice.horizonpay.co/problems/forbidden",
  "title": "Insufficient scope",
  "status": 403,
  "detail": "This credential is missing the invoices:write scope.",
  "instance": "req_7f3c9a1e2b4d4e8a9c6f2d1b0a3e5f71",
  "code": "forbidden"
}

{
  "type": "https://invoice.horizonpay.co/problems/not-found",
  "title": "Not found",
  "status": 404,
  "detail": "Invoice not found.",
  "instance": "req_7f3c9a1e2b4d4e8a9c6f2d1b0a3e5f71",
  "code": "not_found"
}

{
  "type": "https://invoice.horizonpay.co/problems/invalid-state",
  "title": "Invalid state for this operation",
  "status": 409,
  "detail": "This invoice has been finalized and can no longer be edited.",
  "instance": "req_7f3c9a1e2b4d4e8a9c6f2d1b0a3e5f71",
  "code": "invalid_state"
}

{
  "type": "https://invoice.horizonpay.co/problems/validation",
  "title": "Validation failed",
  "status": 422,
  "detail": "Some fields need attention.",
  "instance": "req_7f3c9a1e2b4d4e8a9c6f2d1b0a3e5f71",
  "code": "validation",
  "errors": [
    {
      "path": "due_date",
      "message": "Invalid ISO date"
    }
  ]
}

{
  "type": "https://invoice.horizonpay.co/problems/rate-limited",
  "title": "Too many requests",
  "status": 429,
  "detail": "Rate limit of 120 per 60s exceeded.",
  "instance": "req_7f3c9a1e2b4d4e8a9c6f2d1b0a3e5f71",
  "code": "rate_limited"
}