# Research Findings - 2026 German Law Changes

**Date:** 2026-01-07  
**Sources:** Official government sources, Haufe.de, Betanet.de

## Critical Findings

### 1. Solidaritätszuschlag Freigrenze - UPDATED FOR 2026

**2025 Values:**

- Single taxpayers: €19,950
- Married couples (joint): €39,900

**2026 Values (CORRECT):**

- Single taxpayers: €20,350 ✅
- Married couples (joint): €40,700 ✅

**Current Implementation:**

- Brutto-Netto Calculator: Uses €19,950/€39,900 (2025 values) ❌
- Midijob Calculator: Uses €18,130 (incorrect/outdated) ❌

**Action Required:**

- Update Brutto-Netto calculator to €20,350/€40,700
- Update Midijob calculator to €20,350/€40,700
- Remove all "2025" references

**Source:** [Haufe.de](https://www.haufe.de/id/beitrag/jahreswechsel-20252026-lohnsteuerliche-aenderungen-13-solidaritaetszuschlag-HI17032506.html)

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### 2. Tax Formula - Midijob Calculator Uses Old Formula

**2026 Correct Formula (Brutto-Netto Calculator):**

- Zone 1: ≤12348 € (14% marginal rate)
- Zone 2: 12348-68429 € (progressive: 1693.44 + (zvE - 12348) × 0.24)
- Zone 3: 68429-277825 € (42% flat: 15213.36 + (zvE - 68429) × 0.42)
- Zone 4: >277825 € (45% flat: 103159.68 + (zvE - 277825) × 0.45)

**Current Midijob Calculator (INCORRECT):**

- Zone 2 starts at ≤17005 (old 2025 formula) ❌
- Uses old coefficients: (922.98 _ y + 1400) _ y
- Comment says "Official progressive tax formula 2025"

**Action Required:**

- Update Midijob calculator to use 2026 formula (starts at 12348)
- Update formula coefficients to match Brutto-Netto calculator
- Update comment to "2026"

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### 3. Pflegeversicherung Rates - Discrepancy Found

**Brutto-Netto Calculator:**

- With children: 3.4% total (1.7% employee) ✅
- Without children: 3.75% total (1.875% employee) ✅

**Midijob Calculator:**

- Base rate: 3.6% (comment says "2025") ⚠️
- Childless 23+: 4.2% (3.6% + 0.6% surcharge) ⚠️

**Research Needed:**

- Verify official 2026 Pflegeversicherung rates
- Determine correct rates: 3.4%/3.75% or 3.6%/4.2%?
- Update both calculators to match

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### 4. Arbeitnehmer-Pauschbetrag (werbungskosten)

**Current Value:**

- Midijob: 1230 €/year (comment says "2025")

**Status:** ⚠️ Needs verification - likely unchanged but comment needs update

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### 5. Sonderausgaben-Pauschbetrag

**Current Value:**

- Midijob: 36 €/year (comment says "2025")

**Status:** ⚠️ Needs verification - likely unchanged but comment needs update

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### 6. SK 2 Entlastungsbetrag (Single Parent Relief)

**Current Value:**

- Midijob: 4260 € (comment says "2025")

**Status:** ⚠️ Needs verification - likely unchanged but comment needs update

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### 7. Gleitzone F-Factor

**Current Value:**

- Midijob: 0.6683 (comment says "2025")

**Status:** ⚠️ Likely unchanged but comment needs update

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### 8. Social Security Rates

**Current Values:**

- RV: 18.6% total (9.3% employee) - comment says "2025"
- ALV: 2.6% total (1.3% employee) - comment says "2025"
- KV: 14.6% total (7.3% employee) - comment says "2025"
- PV: See discrepancy above

**Status:** ⚠️ Likely unchanged but comments need update

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## Summary of Required Updates

### Critical (Must Fix Immediately):

1. **Solidaritätszuschlag Freigrenze:**

   - Update Brutto-Netto: 19950 → 20350 (singles), 39900 → 40700 (married)
   - Update Midijob: 18130 → 20350 (singles), add 40700 (married)

2. **Tax Formula (Midijob Calculator):**

   - Update zone boundaries: 17005 → 12348
   - Update formula coefficients to match 2026 formula
   - Update comment from "2025" to "2026"

3. **Pflegeversicherung Rates:**
   - Research and verify correct 2026 rates
   - Update both calculators to match

### High Priority (Update Comments):

1. Update all "2025" comments to "2026" or remove year references
2. Update CSV/PDF export headers from "2025" to "2026"
3. Verify and update werbungskosten, sonderausgaben, SK 2 Entlastungsbetrag comments

### Medium Priority:

1. Verify Gleitzone F-Factor unchanged
2. Verify social security rates unchanged
3. Update all documentation

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## Next Steps

1. ✅ Research complete for Solidaritätszuschlag and tax formula
2. ⚠️ Continue research for Pflegeversicherung rates
3. ⚠️ Verify remaining constants
4. Update all code with correct values
5. Create comprehensive test cases
6. Verify all calculations