InvoicePayload

{
    "document_format": "xrechnung_ubl",
    "document_profile": "EN16931",
    "print_seller_address": false,
    "invoice_number": "RE-2026-001",
    "issue_date": 1775520000,
    "due_date": 1776729600,
    "delivery_date": 1775520000,
    "buyer_reference": "04011000-12345-03",
    "invoice_note": "Projektphase April 2026",
    "tax_category": "AE",
    "tax_exemption_reason": "Steuerschuldnerschaft des Leistungsempfängers",
    "tax_exemption_reason_code": "VATEX-EU-AE",
    "order_reference": "PO-2026-001",
    "payment_means_code": "58",
    "payment_terms_note": "Zahlbar bis 2026-04-21 ohne Abzug.",
    "currency": "EUR",
    "invoice_type_code": "384",
    "preceding_invoice_references": [
        {
            "invoice_number": "RE-2026-001",
            "issue_date": 1775520000
        }
    ],
    "seller": {},
    "buyer": {
        "name": "Kunde GmbH",
        "company_supplement": "z. Hd. Einkauf",
        "vat_id": "DE987654321",
        "street": "Hauptstr. 5",
        "postal_code": "54321",
        "city": "Hamburg",
        "country_code": "DE",
        "email": "buyer@example.com",
        "electronic_address_scheme": "EM",
        "contact_name": "Einkauf"
    },
    "branding": {
        "logo_url": "https://customer.example/logo.png",
        "letterhead_pdf_url": "https://customer.example/letterhead.pdf",
        "letterhead_pdf_base64": "string",
        "letterhead_margins": {
            "top": 63,
            "right": 15,
            "bottom": 30,
            "left": 25
        }
    },
    "items": [
        {
            "name": "Webentwicklung",
            "description": "Implementierung und Review",
            "quantity": 10,
            "unit_code": "HUR",
            "price": 100,
            "tax_rate": 19,
            "service_period_start": 1775001600,
            "service_period_end": 1777507200
        }
    ],
    "allowances": [
        {
            "reason": "Nachlass",
            "reason_code": "95",
            "amount": 100,
            "tax_rate": 19,
            "base_amount": 1000,
            "percentage": 10
        }
    ],
    "prepaid_amount": 500
}