# Calculator Inventory - 2026 Analysis

**Date:** 2026-01-07  
**Purpose:** Complete inventory of all calculator files, their structure, constants, and formulas

## Calculator Files Inventory

### 1. Minijob Calculator

**PHP File:** `v2/pages/tools_minijob_rechner.php`

**JavaScript Files:**

- `v2/js/minijob/constants.js` - All constants (MINIJOB_GRENZE, rates, etc.)
- `v2/js/minijob/calculator.js` - Main calculator logic (4 modes: basic, advanced, employer, vacation)
- `v2/js/minijob/helpers.js` - Helper functions (calculations, validations)
- `v2/js/minijob/utils.js` - Utility functions (formatting, validation)
- `v2/js/minijob/export.js` - Export functionality (PDF, CSV)

**Modes:**

1. Basic Mode - Simple net salary calculation
2. Advanced Mode - Hourly/monthly conversion with detailed calculations
3. Employer Mode - Total employer costs calculation
4. Vacation Mode - Vacation entitlement calculation

**Key Constants:**

- MINIJOB_GRENZE: 603.00 (2026)
- MINDESTLOHN: 13.90 (2026)
- RENTEN_BEITRAG_ARBEITNEHMER: 0.036 (3.6%)
- GEWERBLICH rates (RV, KV, Pauschalsteuer, Umlagen, Unfallversicherung)
- PRIVATHAUSHALT rates (reduced rates)

**Status:** ✅ Constants updated to 2026

---

### 2. Midijob Calculator

**PHP File:** `v2/pages/tools_midijob_rechner.php`

**JavaScript File:**

- `v2/js/tools-midijob-calculator.js` - Single file with all logic

**Modes:**

1. Basic Mode - Simple net salary calculation
2. Advanced Mode - Detailed tax and social security breakdown

**Key Constants:**

- midijobUntergrenze: 603.01 (2026)
- midijobObergrenze: 2000
- minijobGrenze: 603 (2026)
- gleitzoneFactorF: 0.6683 (F-Factor for Gleitzone)
- grundfreibetrag: 12348 (2026)
- kinderfreibetrag: 6828 (2026)
- werbungskosten: 1230 (⚠️ Needs verification - comment says "2025")
- sonderausgaben: 36 (⚠️ Needs verification - comment says "2025")
- Social security rates: RV 18.6%, ALV 2.6%, KV 14.6%, PV 3.6% (⚠️ Comment says "2025")

**Issues Found:**

- ⚠️ Comments mention "2025" in multiple places
- ⚠️ werbungskosten and sonderausgaben comments say "2025" - need verification
- ⚠️ Social security rates comment says "2025" - need verification
- ⚠️ Solidaritätszuschlag freigrenze: 18130 (comment says "2025") - need verification
- ⚠️ CSV/PDF exports mention "2025" in headers

**Status:** ⚠️ Needs verification and updates

---

### 3. Stundenlohn Calculator

**PHP File:** `v2/pages/tools_stundenlohnrechner.php`

**JavaScript File:**

- `v2/js/tools-stundenlohn-calculator.js` - Single file with RATES_2026 object

**Modes:**

1. Simple Mode - Basic hourly wage calculation
2. Pro Mode - Detailed tax and social security calculation

**Key Constants (RATES_2026):**

- MINDESTLOHN: 13.90 (2026)
- MINIJOB_LIMIT: 603 (2026)
- GKV_RATE: 14.6%
- GKV_BBG: 5812.50 (2026)
- RV_RATE: 18.6%
- RV_BBG: 8450 (2026)
- ALV_RATE: 2.6%
- PFLEGEVERSICHERUNG rates (by children count)
- KIRCHENSTEUER rates (BW/BY: 8%, others: 9%)
- SOLIDARITAETSZUSCHLAG: 5.5% (threshold: 19450)

**Status:** ✅ Updated to RATES_2026

---

### 4. Arbeitslosengeld Calculator

**PHP File:** `v2/pages/tools_arbeitslosengeld_rechner.php`

**JavaScript Files:**

- `v2/js/arbeitslosengeld/constants.js` - ALG constants
- `v2/js/arbeitslosengeld/calculator.js` - ALG calculation logic
- `v2/js/arbeitslosengeld/helpers.js` - Helper functions
- `v2/js/arbeitslosengeld/utils.js` - Utility functions
- `v2/js/arbeitslosengeld/export.js` - Export functionality

**Key Constants:**

- MAX_ALG_WEST: 2390 (2026)
- MAX_ALG_EAST: 2320 (2026)
- ALG_PERCENTAGE_NO_CHILDREN: 60%
- ALG_PERCENTAGE_WITH_CHILDREN: 67%
- FREIBETRAG: 165 (monthly side income allowance)
- BRUTTO_TO_NETTO_RATE: 0.80 (80% netto conversion)
- Duration calculation constants (SGB III §127)

**Status:** ✅ Constants appear correct for 2026

---

### 5. Brutto-Netto Calculator

**PHP File:** `v2/pages/tools_bruttonettorechner.php`

**JavaScript Files:**

- May have inline JavaScript or separate file (needs verification)

**Key Constants:**

- Tax brackets (need verification)
- Grundfreibetrag: 12348 (2026)
- Kinderfreibetrag: 6828 (2026)
- BBG values (GKV, RV, ALV)
- Tax rates by tax class

**Status:** ⚠️ Needs analysis

---

### 6. Mehrwertsteuer Calculator

**PHP File:** `v2/pages/tools_mehrwertsteuer_rechner.php`

**JavaScript File:**

- `v2/js/tools-mehrwertsteuer-calculator.js`

**Key Constants:**

- Standard VAT rate: 19% (Germany)
- Reduced VAT rate: 7% (Germany)
- Country-specific rates (AT, CH)
- Kleinunternehmer threshold: 25,000 €

**Status:** ✅ VAT rates unchanged (19%, 7%)

---

### 7. PayPal Calculator

**PHP File:** `v2/pages/tools_paypal_gebuhrenrechner.php`

**JavaScript File:**

- `v2/js/tools-paypal-calculator.js`
- Config file: `v2/api/paypal_fees_config.json` (loaded asynchronously)

**Key Constants:**

- Fee rates by transaction type (personal, business, micropayment, QR code)
- International uplifts
- Currency conversion fees
- Dispute fees
- Withdrawal fees

**Status:** ⚠️ Needs verification (fee structure may change)

---

### 8. Prozentrechner Calculator

**PHP File:** `v2/pages/tools_prozentrechner.php`

**JavaScript File:**

- `v2/js/tools-prozentrechner-calculator.js`

**Modes:**

1. Basic Percentage (X% of Y)
2. Reverse Percentage (X is what % of Y)
3. Percentage Change
4. Percentage Difference
5. Compound Percentage
6. Discount Calculator
7. VAT Calculator (uses 19% default)
8. Profit Margin Calculator

**Key Constants:**

- Default VAT rate: 19% (German standard)

**Status:** ✅ Pure mathematical calculations, no law-dependent constants

---

### 9. Zuschlags Calculator

**PHP File:** `v2/pages/tools_zuschlagsrechner.php`

**JavaScript File:**

- `v2/js/tools-zuschlags-calculator.js`

**Key Constants:**

- Default surcharge rates:
  - Nacht: 25%
  - Sonntag: 50%
  - Feiertag: 100%
  - Samstag: 25%

**Status:** ⚠️ Surcharge rates are tariff-dependent, defaults may need verification

---

### 10. Arbeitszeit Calculator

**PHP File:** `v2/pages/tools_arbeitszeitrechner.php`

**JavaScript File:**

- `v2/js/tools-arbeitszeit-calculator.js`

**Key Constants:**

- Arbeitszeitgesetz thresholds:
  - Break threshold 6h: 30 min
  - Break threshold 9h: 45 min
  - Max daily work: 10h
  - Max weekly work: 48h average
- Industry-specific rules
- Minor protection rules (JArbSchG)

**Status:** ⚠️ Needs verification against Arbeitszeitgesetz 2026

---

### 11. Arbeitstage Calculator

**PHP File:** `v2/pages/tools_arbeitstage_rechner.php`

**JavaScript/Data:**

- Holiday data embedded in PHP file
- OpenHolidays API integration (if applicable)

**Key Constants:**

- Holiday calendar for DE, AT, CH
- Working day calculations
- Bridge day detection

**Status:** ⚠️ Holiday data needs verification for 2026

---

### 12. Urlaubsanspruch Calculator

**PHP File:** `v2/pages/tools_urlaubsanspruchrechner.php`

**Key Constants:**

- Legal minimum: 24 days (6-day week) / 20 days (5-day week)
- BUrlG (Bundesurlaubsgesetz) rules
- Pro-rata calculations

**Status:** ⚠️ Needs analysis

---

### 13. Zinseszins Calculator

**PHP File:** `v2/pages/tools_zinseszinsrechner.php`

**Key Constants:**

- Interest calculation formulas
- Compound interest formulas
- Reverse calculation algorithms

**Status:** ✅ Pure mathematical calculations

---

### 14. TVöD-SuE Calculator

**PHP File:** `v2/pages/tools_tvoed_sue.php`

**Key Constants:**

- Entgelttabellen (salary tables)
- SuE-Zulage rates
- Experience level increments

**Status:** ⚠️ Needs verification for 2026 Entgelttabellen

---

### 15. ROI Calculator Schichtplanung

**PHP File:** `v2/pages/tools_roi_rechner_schichtplanung.php`

**Key Constants:**

- Cost factors
- Time savings calculations
- ROI formulas

**Status:** ⚠️ Needs analysis

---

### 16. Industrieminuten Calculator

**PHP File:** `v2/pages/tools_industrieminuten_rechner.php`

**Key Constants:**

- Industrial minute conversion formulas
- Time calculation rules

**Status:** ⚠️ Needs analysis

---

### 17. Kostenrechner

**PHP File:** `v2/pages/tools_kostenrechner.php`

**Key Constants:**

- Cost calculation formulas
- Overhead factors

**Status:** ⚠️ Needs analysis

---

## Summary of Issues Found

### Critical Issues (Need Immediate Fix):

1. **Midijob Calculator:**
   - Multiple "2025" references in comments
   - werbungskosten: 1230 (comment says "2025") - needs verification
   - sonderausgaben: 36 (comment says "2025") - needs verification
   - Social security rates comment says "2025" - needs verification
   - Solidaritätszuschlag freigrenze: 18130 (comment says "2025") - needs verification
   - CSV/PDF exports mention "2025" in headers

### Needs Verification:

1. **Tax Constants:**

   - werbungskosten (Arbeitnehmer-Pauschbetrag) - verify 2026 value
   - sonderausgaben (Sonderausgaben-Pauschbetrag) - verify 2026 value
   - Solidaritätszuschlag freigrenze - verify 2026 value

2. **Social Security Rates:**

   - RV rate: 18.6% - verify unchanged for 2026
   - ALV rate: 2.6% - verify unchanged for 2026
   - KV rate: 14.6% - verify unchanged for 2026
   - PV rate: 3.6% - verify unchanged for 2026

3. **Other Calculators:**
   - TVöD-SuE Entgelttabellen - verify 2026 tables
   - Holiday calendar - verify 2026 holidays
   - Zuschlags rates - verify if tariff-dependent defaults are correct

---

## Next Steps

1. Research 2026 German law changes for all constants
2. Verify each constant against official sources
3. Update all incorrect values
4. Fix all "2025" references
5. Create comprehensive test cases
6. Document all formulas and legal basis