A sophisticated web application for complete German financial planning - from salary calculation and budgeting to ETF investment modeling and retirement planning.
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The German Financial Planner is a comprehensive, single-page web application designed specifically for the German market. It creates a seamless financial planning journey that connects every aspect of your financial life - from understanding your true earning capacity to planning your retirement lifestyle.
Unlike standalone calculators, this application creates a connected workflow where each phase builds upon the previous one:
Tax Calculator → Budget Planning → Investment Modeling → Retirement Planning
Each phase automatically transfers relevant data to the next, creating a cohesive financial plan where your salary calculations inform your budget, your budget determines your investment capacity, and your investment results shape your retirement strategy.
- 🔗 Seamless Data Flow: Each phase connects to the next with automatic data transfer
- 🇩🇪 German Tax Law Compliant: Full implementation of 2025 German tax rates, social insurance, and ETF taxation rules
- 📈 Mathematical Precision: Uses exact formulas including Newton-Raphson iteration for portfolio calculations
- 🔄 Complete Lifecycle: From salary calculation to retirement planning in one integrated tool
- 📊 Advanced Visualizations: Interactive charts with Chart.js for comprehensive financial analysis
- 💾 Data Persistence: Profile management and scenario comparisons with local storage
- 2025 Tax Compliance: Official German tax brackets, social insurance rates
- All 16 Federal States: State-specific church tax rates
- Progressive Tax Modeling: Realistic salary increase impact on net income
- Complete Deductions: Health, pension, unemployment, and care insurance
- 🔗 Automatic Transfer: Net salary flows directly into budget planning
- Comprehensive Categories: Income, fixed costs, variable expenses
- Flexible Periods: Monthly/yearly input options for all categories
- Profile Management: Save, load, and manage multiple budget scenarios
- Visual Analysis: Interactive pie charts for expense distribution
- Smart Savings Allocation: Fixed amount or percentage-based savings planning
- 🔗 Seamless Integration: Available savings automatically become your ETF investment rate
- Multi-Scenario Comparison: Compare up to 4 investment strategies side-by-side
- German ETF Taxation: Vorabpauschale (advance lump sum tax) and Teilfreistellung (partial exemption)
- Progressive Salary Growth: Uses tax calculator data to model realistic salary increases
- Interactive Visualizations:
- Scenario comparison charts
- Contributions vs. gains analysis
- Real vs. nominal value tracking
- 🔗 Capital Transfer: Final portfolio value feeds directly into retirement planning
- Precise Mathematical Modeling: Direct annuity formulas with inflation adjustment
- German Capital Gains Tax: Accurate Abgeltungssteuer calculations
- Integrated Timeline: Seamless visualization from accumulation to withdrawal
- Multiple Chart Views: Portfolio development and cash flow analysis
- 🔗 Full Integration: Uses accumulated capital and contribution history for precise calculations
- Complete Lifecycle Analysis: Visualize entire financial journey from salary to retirement
- Metrics Radar Chart: Compare key performance indicators across all phases
- Parameter Comparison Tables: Detailed side-by-side analysis of different strategies
- Export Capabilities: CSV and JSON data export for external analysis
- Income Tax Brackets: Complete progressive tax calculation
- Social Insurance: All current rates and contribution ceilings
- Church Tax: State-specific rates (8% or 9%)
- Care Insurance: Age and family status considerations
- Vorabpauschale: Advance lump sum tax for accumulating ETFs
- Teilfreistellung: 30% partial tax exemption for equity funds
- Sparerpauschbetrag: €1,000 annual tax-free allowance
- Abgeltungssteuer: 25% capital gains tax with proper cost basis tracking
- Modern web browser (Chrome, Firefox, Safari, Edge)
- No server installation required - runs entirely in the browser
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Clone the repository
git clone https://github.com/yourusername/german-financial-planner.git cd german-financial-planner -
Open the application
# Open in your default browser open public/etf_savings.html # Or navigate to the file in your browser # file:///path/to/german-financial-planner/public/etf_savings.html
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Follow the connected financial journey!
- Start with Tax Calculator → Get your true net income
- Flow to Budget Planning → Determine investment capacity
- Build Investment Strategy → Model wealth accumulation
- Plan Retirement → Design withdrawal strategy
- Compare Scenarios → Optimize your complete financial plan
german-financial-planner/
├── public/ # Main application files
│ ├── etf_savings.html # Primary application file
│ ├── app.js # Core JavaScript logic (9,400+ lines)
│ ├── style.css # Comprehensive styling
│ └── hover_mouse_example.html # Chart.js example
├── docs/ # Comprehensive documentation
│ ├── ETF_Calculator_Documentation.md
│ ├── FORMULAS.md # Mathematical formulas reference
│ ├── features/ # Feature specifications
│ └── feature-plans/ # Development roadmap
├── LICENSE # Apache 2.0 License
└── README.md # This file
This application is designed as an integrated workflow where each phase builds on the previous one. Follow this connected journey for comprehensive financial planning:
- Enter your gross annual salary in the Tax Calculator
- Select tax class, federal state, and personal details
- See your real net income after German taxes and social insurance
- Click "Transfer to ETF Calculator" → Automatically flows to Phase 2
- Your net salary is pre-filled from the tax calculator
- Add additional income sources and categorize all expenses
- Watch the budget visualization update in real-time
- Determine your optimal savings rate (fixed amount or percentage)
- Click "Apply Savings Rate" → Automatically flows to Phase 3
- Your monthly savings rate is pre-filled from budget planning
- Your gross salary data enables realistic salary growth modeling
- Create multiple scenarios to compare different strategies
- Watch your wealth grow over time with German tax considerations
- Automatic sync → Final capital flows to Phase 4
- Your accumulated capital is automatically imported
- Your total contributions are calculated from investment history
- Model withdrawal strategies with inflation and tax considerations
- Visualize the complete timeline from accumulation to depletion
- View side-by-side comparisons of different life strategies
- Analyze the complete financial lifecycle from salary to retirement
- Use radar charts to compare key metrics across scenarios
- Export your complete financial plan for further analysis
- Salary → Budget: Net income automatically updates budget calculations
- Budget → Investment: Available savings becomes your investment rate
- Investment → Retirement: Final capital and contribution history flow seamlessly
- Real-time Sync: Changes in earlier phases automatically update later calculations
- Frontend: Vanilla JavaScript (ES6+), HTML5, CSS3
- Charts: Chart.js 4.x for interactive visualizations
- Storage: Browser localStorage for data persistence
- Architecture: Single-page application with modular design
- German Number Formatting: Proper comma decimal separators
- Real-time Calculations: Instant feedback with debounced updates
- Mathematical Precision: Newton-Raphson iteration for exact calculations
- Error Handling: Comprehensive input validation and error recovery
- Debounced calculation updates
- Efficient chart rendering and updates
- Smart caching of calculation results
- Minimal DOM manipulation
- ETF Calculator Documentation: Complete application guide
- Mathematical Formulas: All calculation formulas with explanations
- Features Overview: Detailed feature specifications
- Tax Calculation Fixes: German tax implementation details
- Chart Issues: Chart.js integration notes
The application supports easy extension of investment scenarios:
// Add new scenario template
const newScenario = {
id: 'E',
name: 'Custom Strategy',
color: '#9b59b6',
inputs: {},
yearlyData: [],
results: {}
};German tax rates and rules are centralized for easy updates:
// Update tax brackets in app.js
const taxBrackets2026 = {
basicAllowance: 12096, // Update annually
brackets: [/* new brackets */]
};We welcome contributions! Here's how you can help:
- Fork the repository
- Create a feature branch (
git checkout -b feature/AmazingFeature) - Commit your changes (
git commit -m 'Add AmazingFeature') - Push to the branch (
git push origin feature/AmazingFeature) - Open a Pull Request
- Follow German financial regulations and tax law
- Maintain mathematical precision in calculations
- Include comprehensive documentation
- Test with various German tax scenarios
This project is licensed under the Apache License 2.0 - see the LICENSE file for details.
Copyright 2025 German Financial Planner Contributors
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
- German Federal Ministry of Finance for official tax rate publications
- Chart.js Community for excellent visualization capabilities
- Finanzfluss for the initial inspiration and for providing high-quality, free financial calculators accessible to everyone
- Cursor for making the development process 10x more efficient 🚀
⭐ Star this project if you find it helpful!
Built with ❤️ for the German financial planning community