# Luxembourg Vat XML > Generate Luxembourg quarterly VAT declarations (TVA_DECT) in eCDF XML format for AED submission. Use when working with Luxembourg VAT returns, eCDF XML generation, or fixing VAT declaration validation errors for Luxembourg businesses. - Skill: `ticruz38/luxembourg-vat-xml` (Agent Skill, multi-file: 6 files) - Install (CLI): `npx skillmds@latest add ticruz38/luxembourg-vat-xml` - Raw SKILL.md: https://api.skillmd.com/api/skills/ticruz38/luxembourg-vat-xml/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: ticruz38 (https://skillmd.com/u/ticruz38) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/ticruz38/luxembourg-vat-xml --- # Luxembourg VAT Declarations (eCDF) Generate Luxembourg quarterly VAT declarations (TVA_DECT) in eCDF XML format for AED submission. ## Quick Start 1. **Copy the example config:** ```bash cp vat_config.example.json vat_config.json ``` 2. **Edit `vat_config.json`** with your company details: - `MatrNbr`: Your matricule number - `RCSNbr`: Your RCS number - `VATNbr`: Your VAT number - `eCDFPrefix`: Your eCDF prefix 3. **Prepare your CSV file** with expenses (see `example_csv_format.md`) 4. **Run the generator:** ```bash python3 generate_vat_declarations.py ``` ## Files - `generate_vat_declarations.py` - Main script - `vat_config.example.json` - Configuration template - `example_csv_format.md` - CSV format documentation - `FIELD_FORMULAS.md` - eCDF field formulas reference --- ## Critical Lessons Learned > **⚠️ CRITICAL**: This skill documents hard-learned lessons from fixing VAT declaration errors. Read completely before generating XML. ## Overview Generate Luxembourg quarterly VAT declarations (TVA_DECT) in eCDF XML format for AED submission. Based on painful real-world debugging of validation errors. --- ## Critical Lessons Learned (READ FIRST) ### 1. Field Order is CRITICAL The eCDF validator checks **exact field sequence**, not just presence. One field out of order = rejection. **Correct Order:** ``` Numeric 012-105 → Choice 204/205/491/492/493 → Numeric 403/418/453 → Numeric 042/416/417/451/452 ``` **Common Mistake:** ```xml 0,00 1 1 0 0 0 0 0 0 0 0,00 0,00 0,00 0,00 0,00 ``` ### 2. Fields 491/492/493 - Year Dependent ⚠️ **Important**: These fields may or may not be required depending on the declaration year: **For 2024 declarations:** Only 204 and 205 are needed ```xml 1 0 ``` **For 2025+ declarations:** All 5 Choice fields may be required ```xml 1 0 0 0 0 ``` **Error if wrong:** `"Les champs suivants ne sont pas autorisés, ou mal placés: 491, 492, 493"` **Solution:** Try without 491/492/493 first. If you get this error, add them. ### 3. Rounding is a Trap The validator adds **rounded XML values** to check formulas, not raw float values. **Example of failure:** ``` 462 = 3.513900 → XML shows "3,51" 464 = 11.281427 → XML shows "11,28" Validator computes: 3,51 + 11,28 = 14,79 But if you calculate from unrounded: 410 = 3.513900 + 11.281427 = 14.795327 → XML shows "14,80" 14,80 ≠ 14,79 → VALIDATION ERROR! ``` **Solution:** Calculate derived fields from **already-rounded** components: ```python field_410 = round(field_462, 2) + round(field_464, 2) ``` ### 4. Formula Reference (eCDF Requirements) | Field | Formula | Notes | |-------|---------|-------| | **409** | 436 + 435 + 463 + 765 | Total services requiring reverse charge | | **410** | 462 + 464 + 766 | Total VAT on services received | | **076** | 046 + 056 + 407 + 410 + 768 + 227 | Total output VAT | | **093** | 458 + 459 + 460 + 090 + 461 + 092 + 228 | Total input VAT | | **461** | 464 + 462 + 766 | Deductible reverse charge | | **463** | 751 + 951 + 753 + 953 + 755 + 955 + 441 + 445 | Non-EU base | | **464** | 752 + 952 + 754 + 954 + 756 + 956 + 442 | Non-EU VAT | ### 5. Invoice Categorization Matters **Common mistake**: Labeling coworking as "Rent - No VAT" when it's actually **services with 17% VAT**. **Real example:** - The Office City invoices said "Rent" but were actually "Coworking + Business Address" - Difference: €59.13/month × 12 months = **€709.56 in claimable VAT nearly lost!** Always verify actual VAT amount on PDF, don't rely on description. --- ## Usage ### Quick Start ```python # See generate_vat_declarations.py for full implementation python3 generate_vat_declarations.py ``` ### Required Files 1. **CSV file** with columns: - Quarter, Provider, Total Amount (EUR), VAT Rate, VAT Amount, Net Amount, Currency, Notes 2. **Company config** (vat_config.json): ```json { "company": { "MatrNbr": "YOUR_MATRICULE_NUMBER", "RCSNbr": "YOUR_RCS_NUMBER", "VATNbr": "YOUR_VAT_NUMBER", "eCDFPrefix": "YOUR_ECDF_PREFIX" } } ``` ### VAT Categories | Provider Type | Fields | Treatment | |---------------|--------|-----------| | Luxembourg suppliers | 458 | Direct VAT deduction | | Non-EU services (USA) | 751/752/463/464/461 | Reverse charge at 17% | | EU services (France, etc) | 741/742/436/462/461 | Reverse charge at 17% | --- ## Validation Checklist Before submitting, verify: - [ ] All 5 Choice fields present (204, 205, 491, 492, 493) - [ ] Choice fields in correct position (after 105, before 403) - [ ] Fields 042/416/417/451/452 at very end - [ ] Fields 403/418/453 as integers ("0" not "0,00") - [ ] Formulas validate with rounded values - [ ] No negative values where not expected - [ ] Exchange rates applied for USD invoices --- ## Error Messages Decoded | Error | Meaning | Fix | |-------|---------|-----| | "Champs 491, 492, 493 non autorisés ou mal placés" | Choice fields missing/wrong position | Add all 5 Choice fields in correct order | | "Champ 409 = champs (436 + 435 + 463 + 765)" | Formula error for field 409 | Calculate from rounded components | | "Champ 410 = champs (462 + 464 + 766)" | Formula error for field 410 | Calculate from rounded components | | "Champ 076 = champs (046 + 056 + 407 + 410 + 768 + 227)" | Formula error for field 076 | Set 076 = 410 for expense-only declarations | --- ## Files in This Skill - `generate_vat_declarations.py` - Working script with all fixes - `vat_config.json` - Company configuration template - `example_csv_format.md` - CSV column requirements --- ## Real-World Debugging Tips 1. **Test one quarter first** - Don't generate all 4 until one passes 2. **Check exact error message** - It tells you which field and expected formula 3. **Compare with working reference** - Line-by-line diff of XML structure 4. **Watch for floating point** - Python float math can cause 0.01 rounding errors 5. **Verify invoice PDFs** - Don't trust descriptions, check actual VAT amounts --- ## Generated With - Date: 2024-01-29 - Tested: Successfully validated all 4 quarters 2024 - Total VAT recovered: €1,154.29 (was €372.85 before fixes)