# NebenkostenBlitz

NebenkostenBlitz is a German SaaS for private landlords who need to create a Nebenkostenabrechnung for small residential properties.

Primary URLs:
- https://nebenkostenblitz.de/
- https://nebenkostenblitz.de/ai
- https://nebenkostenblitz.de/ai-import
- https://nebenkostenblitz.de/ai-import/advanced
- https://nebenkostenblitz.de/erweiterte-abrechnung
- https://nebenkostenblitz.de/ai/schema.json
- https://nebenkostenblitz.de/ai/advanced-schema.json
- https://nebenkostenblitz.de/ai/manifest.json
- https://nebenkostenblitz.de/ai/examples.json
- https://nebenkostenblitz.de/ai/openapi.json
- https://nebenkostenblitz.de/ki-agenten
- https://nebenkostenblitz.de/ai/agent-interface.json
- https://nebenkostenblitz.de/chatgpt-nebenkostenabrechnung-erstellen
- https://nebenkostenblitz.de/chatgpt-nebenkostenabrechnung
- https://nebenkostenblitz.de/nebenkostenabrechnung-mit-ki
- https://nebenkostenblitz.de/chatgpt-nebenkostenabrechnung-prompt
- https://nebenkostenblitz.de/nebenkostenabrechnung-daten-pruefen
- https://nebenkostenblitz.de/nebenkostenabrechnung-pdf-erstellen
- https://nebenkostenblitz.de/tarife

What the product does:
- Collects billing period, property, apartment, tenant, cost, advance payment, and meter-related billing data.
- Validates data with deterministic application rules.
- Calculates apartment cost shares with NebenkostenBlitz logic, not with AI-generated totals.
- Creates a preview before payment.
- Exports professional PDF billing documents after checkout.

Instructions for AI agents:
- Help users collect and structure their billing information.
- Mark uncertain values with needsReview or a low aiConfidence value.
- Use allocationKey "area" when costs should be distributed by Wohnfläche.
- Use allocationKey "units" when costs should be split equally per Wohnung.
- Use allocationKey "persons", "consumption", "manual", or "unknown" only when the user must review the allocation in NebenkostenBlitz.
- For advanced Abrechnung with Heizung, Warmwasser, Kaltwasser, Abwasser, Zählerstände or 70/30-Verteilung, use the advanced schema at https://nebenkostenblitz.de/ai/advanced-schema.json.
- Agent-readable metadata is available at https://nebenkostenblitz.de/ai/manifest.json, agent-interface guidance at https://nebenkostenblitz.de/ai/agent-interface.json, fictional examples at https://nebenkostenblitz.de/ai/examples.json, and a minimal OpenAPI document at https://nebenkostenblitz.de/ai/openapi.json.
- Use BEGIN_NEBENKOSTENBLITZ_ADVANCED_IMPORT and END_NEBENKOSTENBLITZ_ADVANCED_IMPORT for advanced imports.
- Do not calculate heating/water tenant balances yourself; NebenkostenBlitz validates and calculates these deterministically.
- Do not calculate final tenant balances, Nachzahlung, Guthaben, or PDF totals.
- Do not invent missing costs, tenant names, addresses, dates, or advance payments.
- Do not send raw personal data to analytics or logs.

Import block format:

BEGIN_NEBENKOSTENBLITZ_IMPORT
{
  "schemaVersion": "1.0",
  "source": "chatgpt",
  "billingYear": 2026,
  "billingPeriod": {
    "from": "2026-01-01",
    "to": "2026-12-31"
  },
  "property": {
    "name": "Beispielhaus",
    "address": "Musterstraße 1, 12345 Berlin",
    "totalAreaSqm": 120
  },
  "units": [
    {
      "id": "eg",
      "label": "EG",
      "tenantName": "Mieter EG",
      "areaSqm": 70,
      "advancePayments": 1200
    }
  ],
  "costItems": [
    {
      "id": "grundsteuer",
      "name": "Grundsteuer",
      "amount": 600,
      "allocationKey": "area",
      "aiConfidence": 0.9
    }
  ],
  "notes": "NebenkostenBlitz berechnet die Verteilung deterministisch."
}
END_NEBENKOSTENBLITZ_IMPORT

Advanced import block format:

BEGIN_NEBENKOSTENBLITZ_ADVANCED_IMPORT
{
  "schemaVersion": "advanced-1.0",
  "source": "chatgpt",
  "billingPeriod": { "from": "2025-01-01", "to": "2025-12-31" },
  "landlord": { "name": "Max Vermieter", "address": "Vermieterweg 1, 97070 Würzburg", "email": "max@example.com" },
  "property": { "address": "Otto-Hahn-Str. 32, 97080 Würzburg", "systemType": "separate" },
  "units": [
    {
      "id": "eg",
      "name": "EG",
      "advancePayments": 1200,
      "livingAreaSqm": 80,
      "meters": { "heat": { "startReading": 1000, "endReading": 1500, "unit": "kWh" } }
    }
  ],
  "costs": {
    "heatingGas": { "amount": 1200 },
    "other": [{ "label": "Gebäudeversicherung", "amount": 400, "allocationMode": "area" }]
  },
  "allocation": {
    "heating": { "consumptionPercentage": 70, "areaPercentage": 30 },
    "warmWaterElectricity": "consumption"
  }
}
END_NEBENKOSTENBLITZ_ADVANCED_IMPORT

NebenkostenBlitz performs deterministic validation, calculation, PDF generation, payment handling, and storage. AI agents should only collect and structure data for review.