🇩🇪 Rechly-DE-3B: 100% Local German Accounting & E-Rechnung AI

The specialized 3-Billion parameter Small Language Model (SLM) for German Invoicing, the 2025/2026 E-Rechnung Mandate (EN 16931, XRechnung 3.0, ZUGFeRD 2.3), GoBD Pre-Audit, and DATEV SKR03/04 Bookkeeping.

Runs 100% on-device on Apple Silicon MacBooks, lightweight Linux VPS, or standard CPUs with zero cloud dependencies and < 2.5 GB RAM.

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⚡ 10-Second Quickstart

1. Run instantly with Ollama:

ollama run jonprompter/rechly-de-3b

2. Test an invoice in one line:

ollama run jonprompter/rechly-de-3b "Rechnung an Kanzlei Schmidt: 10 Std. IT-Forensik à 140€ und 1x Anfahrt Pauschal 80€, zahlbar in 14 Tagen."

3. Python 4-Liner:

import requests

resp = requests.post("http://localhost:11434/api/chat", json={
    "model": "jonprompter/rechly-de-3b",
    "messages": [{"role": "user", "content": "Kategorisiere für SKR03 und SKR04: 'Geschäftsessen im Restaurant 140€ mit Kunde'"}],
    "stream": False,
    "options": {"temperature": 0.0}
})
print(resp.json()["message"]["content"])
# Output: {"category": "Bewirtung", "skr03_account": "4650", "skr04_account": "6640", "deductible_percent": 70, "vat_rate": 19}

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🏛️ The Rechly Model Family: 3 Tiers for Every Infrastructure

# Pull & Run Flagship (3B)
ollama run jonprompter/rechly-de-3b

# Run Slim (1.5B) - 1 GB VPS
ollama create rechly-de-1.5b -f Modelfile.1.5b
ollama run rechly-de-1.5b

# Run Nano (0.5B) - 500 MB RAM / Raspberry Pi
ollama create rechly-de-0.5b -f Modelfile.0.5b
ollama run rechly-de-0.5b

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🚨 Why Rechly-DE-3B? The German E-Rechnung 2025/2026 Challenge

Under the Wachstumschancengesetz (§ 14 UStG), traditional paper invoices and standard unstructured PDFs are legally obsolete for domestic B2B transactions. Over 3.5 million German companies are legally mandated to process structured E-Rechnungen (EN 16931, XRechnung 3.0, ZUGFeRD 2.3).

The Challenge with Cloud AI Services:

• Privacy & Data Governance Concerns: Invoices, client names, hourly rates, and bank accounts contain sensitive personal and financial data. Processing them on third-party cloud servers requires Data Processing Agreements (DPA / AVV) and careful risk assessment under GDPR / DSGVO.
• Token Costs: Processing verbose XML structures, long invoices, and receipt scans can lead to significant ongoing API operational costs.
• Domain Accuracy on German Tax Law: General-purpose foundation models frequently misapply German statutory rules, such as confusing DATEV account numbers, misapplying the 70% entertainment expense deductibility cap (§ 4 Abs. 5 Nr. 2 EStG), or omitting statutory tax-exemption notices (§ 19 UStG, § 13b UStG).

The Rechly-DE-3B Architecture:

• 100% Local & Offline (Zero Data Egress): Operates entirely on-device, preventing external data transmission and supporting the principle of Data Protection by Design (Art. 25 GDPR).
• Specialized Accounting Adaptation: Fine-tuned on curated statutory German tax law and 30+ commonly used DATEV SKR03/SKR04 accounts.
• Lightweight Footprint: 1.93 GB GGUF Q4_K_M running at 60–80+ tokens/sec on Apple Silicon or standard CPU with < 2.5 GB RAM.
• Formal Grammars: Ships with pre-configured GBNF grammars (grammars/*.gbnf) for mathematically constrained JSON schema adherence.

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📊 Internal Synthetic Evaluation Suite: Rechly-DE-3B vs. General LLMs

Rechly-DE-3B was evaluated against base foundation models using an internal synthetic test suite of 77 reproducible test vectors covering German tax provisions, DATEV account assignment, and formal JSON formatting. (Note: This is an internal project test suite and does not represent an external regulatory certification).

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🎯 10 Core Capabilities & Built-in Modules

1. Text-to-Invoice (Strict JSON Extraction)

Converts unstructured German voice notes, emails, or messages into structured, validated JSON:

• Extracts client names, quantities, units, prices, due dates, and tax rates (19%, 7%, 0%).
• Automatically detects tax exemptions: § 19 UStG (Kleinunternehmer), § 13b UStG (Reverse Charge), § 4 Nr. 1b (EU B2B), and § 4 Nr. 1a (Drittland Export).

2. ZUGFeRD 2.3 & Factur-X PDF/A-3 Hybrid Invoice Generator

Generates ready-to-send hybrid electronic invoices matching the 2025/2026 German mandate:

• Combines a beautiful, human-readable visual PDF with an embedded, machine-readable factur-x.xml (EN 16931).
• Associated file (/AF) registration and ISO 19005-3 compliant XMP metadata.
• Generated via scripts/zugferd_generator.py or the /api/zugferd-generate endpoint.

3. Multimodal Receipt OCR to DATEV Bookings (Vision SLM)

Turns photos of crumpled receipts, restaurant slips (Bewirtungsbelege), fuel tickets (Tankbons), and scanned invoices directly into accounting entries:

• Preprocesses and cleans receipt images with Pillow.
• Extracts line items, merchant name, date, tax rate, and totals via local vision SLM (e.g., Qwen2.5-VL 3B).
• Directly outputs ready-to-import DATEV EXTF CSV rows and GoBD pre-audit risk evaluations via scripts/receipt_vision_ocr.py.

4. DATEV SKR03 & SKR04 Expense Accounts (30+ Standard Accounts)

Maps natural language expense descriptions to standard German 4-digit chart accounts with statutory deductibility percentages:

• Bewirtung (Restaurants): SKR03 4650, SKR04 6640 (70% abzugsfähig gem. § 4 Abs. 5 Nr. 2 EStG, 100% Vorsteuer)
• SaaS & Cloud Software: SKR03 4964, SKR04 6837 (100% Betriebsausgabe)
• GWG Geringwertige Wirtschaftsgüter (< 800€): SKR03 0480, SKR04 0670
• Treibstoff & Kfz-Kosten: SKR03 4530, SKR04 6530
• Telekommunikation & Internet: SKR03 4920, SKR04 6805
• Reisekosten Fahrt (Bahn 7% MwSt): SKR03 4673, SKR04 6673
• Reisekosten Hotel (Übernachtung 7% MwSt): SKR03 4660, SKR04 6660
• Fachliteratur (7% MwSt): SKR03 4940, SKR04 6815
• Bankgebühren (0% steuerfrei): SKR03 4970 / 2100, SKR04 6855 / 7300

5. GoBD § 14 Abs. 4 UStG Pre-Audit Inspector

Pre-screens incoming supplier invoices for all 10 statutory mandatory fields to prevent tax auditors from disallowing input VAT deduction (Vorsteuerabzug):

• Flags missing Steuernummer/USt-IdNr, missing consecutive invoice numbers, and missing delivery periods (Leistungszeitpunkt).
• Outputs risk categories: KEIN_RISIKO, MITTEL, HOCH with legal remediation instructions.

6. DATEV Buchungssatz CSV Generator (EXTF)

Generates ready-to-import semicolon-separated DATEV EXTF ASCII lines for automated batch import into DATEV Rechnungswesen and Kanzlei-Rechnungswesen:

142,80;S;EUR;;;;4964;1200;9;1502;RE-2025-081;;;Google Workspace SaaS

7. B2B Line Item Rewriter

Transforms informal craftsman or developer shorthand into audit-proof, GoBD-compliant commercial invoice lines:

• Input: "klo repariert und dichtung gewechselt"
• Output: "Fachgerechte Sanitär-Instandsetzung: Austausch schadhafter Dichtungen, mechanische Rohrreinigung sowie abschließende Dichtheitsprüfung."

8. Multi-Stage Mahnwesen (Dunning Letters)

Drafts legally disciplined payment reminders across German commercial stages:

• Stufe 1: Freundliche Zahlungserinnerung (diplomatisch, ohne Mahngebühren)
• Stufe 2: 1. Mahnung (formell mit 7-Tage-Nachfrist)
• Stufe 3: Letzte Mahnung (bestimmt, Ankündigung gerichtlicher Schritte und Inkassokosten)

9. DATEV EXTF 700 Batch & DUO ZIP Export Utility

Exports batches of booking entries according to the DATEV Format 700 specification (independent community implementation):

• 27-to-31-column semicolon format with standard BU-Schlüssel (9, 8, 3, 2, 94).
• DATEV Unternehmen online (DUO) compatible ZIP structure containing EXTF_Buchungsstapel.csv and XML manifest (document.xml).
• Dual-encoding support (CP1252 and UTF-8-SIG) for compatibility with DATEV Kanzlei-Rechnungswesen import tools.

10. Mathematical Reconciler & § 35a Handwerkerleistungen Splitter

Applies commercial rounding (§ 35 UStDV) and statutory tax reductions:

• Reconciles mixed-rate tax groupings (19%, 7%, 0%) with cent-exact arithmetic.
• Automatically isolates craftsman labor and travel costs from materials under § 35a Abs. 3 EStG, calculating the eligible 20% direct tax reduction (capped at 1.200 € p.a.).

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🔬 DPO / ORPO Preference Alignment Dataset

To reduce legal hallucinations on German accounting rules, Rechly-DE-3B includes a curated preference alignment dataset (data/rechly_preference_pairs.jsonl) with 101 (prompt, chosen, rejected) pairs.

• Negative samples (rejected) capture critical real-world failure modes:
  • Charging 19% VAT on Kleinunternehmer invoices (violating § 19 UStG and triggering § 14c tax liabilities).
  • Claiming 100% tax deduction on client entertainment (violating § 4 Abs. 5 Nr. 2 EStG).
  • Approving vendor invoices without a valid Steuernummer.
  • Inventing non-existent 4-digit DATEV codes.
• Training Harness (scripts/train_orpo.py): Single-stage ORPO alignment via Hugging Face TRL and PEFT/QLoRA.

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🔒 GBNF Grammars: Formal Schema Constraints

In financial production systems, JSON schema validation cannot rely on unconstrained generation. Rechly-DE-3B includes formal GBNF (GGML BNF) grammar files:

• grammars/invoice.gbnf: Constrains token sampling strictly to valid invoice JSON.
• grammars/expense.gbnf: Restricts outputs to verified 4-digit DATEV accounts and valid tax rates.
• grammars/xrechnung.gbnf: Enforces valid EN 16931 / XRechnung 3.0 structure.
• grammars/gobd_audit.gbnf: Enforces structured audit reports.

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💻 Integration Examples

Python (OpenAI-compatible)

from openai import OpenAI

client = OpenAI(
    base_url="http://localhost:11434/v1",
    api_key="ollama"  # not needed locally
)

response = client.chat.completions.create(
    model="jonprompter/rechly-de-3b",
    messages=[
        {"role": "user", "content": "Optimiere diese Tätigkeitsbeschreibung für die Rechnungsstellung: 'homepage schneller gemacht und alte bilder gelöscht'"}
    ],
    temperature=0.0
)
print(response.choices[0].message.content)

cURL

curl -X POST http://localhost:11434/api/chat -d '{
  "model": "jonprompter/rechly-de-3b",
  "messages": [{"role": "user", "content": "Erstelle eine Mahnung Stufe 1 an Kanzlei Schmidt über 1.200€ seit 10 Tagen fällig."}],
  "stream": false,
  "options": {"temperature": 0.0}
}'

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👥 Who Is This For?

1. Developers & SaaS Founders: Build automated German invoicing and E-Rechnung features into your CRM, ERP, or SaaS without paying OpenAI API fees.
2. Freelancers & Small Businesses (Selbstständige / KMU): Automate invoice drafting and expense categorization on your own local device without third-party cloud data exposure.
3. Tax Advisors & Bookkeepers (Steuerberater / Kanzleien): Speed up receipt pre-sorting and generate DATEV EXTF-compatible semicolon CSV files ready for import review.
4. Enterprises & Privacy-Conscious Organizations: Run specialized accounting assistants on air-gapped on-premise infrastructure with zero risk of external cloud data egress.

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⚖️ Legal, GDPR & Benchmark Disclaimers

1. No Tax Advice (Keine Steuerberatung)

Rechly-DE-3B provides automated text extraction and schema-constrained formatting based on public German statutory standards (UStG, GoBD, EStG). It is an open-source productivity tool and does not replace certified tax advice by an authorized German Steuerberater or certified tax professional (gem. StBerG / RDG).

2. GDPR / DSGVO & Data Protection by Design

*The model runs 100% locally on-device with zero external network egress to third-party AI APIs, supporting technical data confidentiality and the principle of Data Protection by Design & Default (Art. 25 GDPR / DSGVO). However, legal GDPR compliance is an organizational responsibility of the entity acting as the Data Controller (Art. 4(7) GDPR). Using local software does not automatically grant a certification of full organizational compliance (e.g. data retention policies, access permissions, and lawful basis under Art. 6 GDPR).*

3. Internal Synthetic Benchmark Notice

All benchmark scores (including the 77-case evaluation suite) represent internal, self-reported synthetic test suites developed within this repository to verify statutory edge cases and schema validity. They do not constitute an independent audit, official government benchmark, or certification by any statutory authority, standard-setting body, or accredited testing laboratory.

4. Trademarks & Third-Party Notice

DATEV® is a registered trademark of DATEV eG. ZUGFeRD is a registered specification of the Forum elektronische Rechnung Deutschland (FeRD / AWV e.V.). Factur-X is a registered trademark of FNFE-MPE. This project is an independent open-source community toolkit and is not affiliated with, endorsed by, or certified by DATEV eG, FeRD, or FNFE-MPE.

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📜 Citation & Open Source

@misc{rechly_de_3b_2026,
  author = {Rechly Team and Contributors},
  title = {Rechly-DE-3B: A Specialized Open Small Language Model for German Invoicing, GoBD Compliance, E-Rechnung, and DATEV Bookkeeping},
  year = {2026},
  publisher = {Hugging Face and GitHub},
  howpublished = {\url{https://huggingface.co/jonprompter/rechly-de-3b}}
}

⭐ If you find Rechly-DE-3B useful, please star the model on Hugging Face and GitHub to support independent German open-source AI!