This Python script calculates compound interest over a specified number of years, comparing a simple investement in a depot to a private pension contract in germany. These private contracts often have tax benefits; this program allows to compute whether these tax benefits are offset by the contract fees. This program considering different investment scenarios, tax rates, fees, and portfolio management strategies.
- Monthly Contributions: Handles periodic contributions that can increment annually.
- Taxable and Non-Taxable Growth: Separates already taxed gains from untaxed interest for accurate computation.
- Portfolio Reorganization: Simulates periodic taxation events due to portfolio restructuring.
- Fee Structures: Supports dynamic monthly fees and fund-specific fees (e.g., ETF fees).
- Custom Tax Rates: Applies different tax rates for regular and contractual scenarios.
- Annual Tax-Free Allowances: Incorporates tax-free allowances into calculations.
This code can generate visualization helping the interpretation of the simulation
- Python 3.x
- Numpy
- Matplotlib
Install dependencies using:
pip install matplotlib numpyThe compute_interest function accepts the following parameters:
monthly_rate: Monthly contribution amount.yrly_interest: Annual interest rate (as a percentage).yrs: Duration of the investment in years.rate_increment: Yearly percentage increase in contributions.reorganize_portfolio_times: Number of portfolio restructuring events. This triggers taxation.tax_rate: Tax rate (as a percentage).monthly_fees: A 2D array specifying monthly fees as tuples:(number_of_months, fee_amount).yrly_taxfree: Annual tax-free allowance.
Adjustable parameters for investment comparison:
yrs = 33 # Investment period in years
montly_rate = 150 # Monthly contribution in euros
dynamic = 0 # Annual contribution increase percentage
avg_interest = 9.1 # Average yearly interest rate (percent)
avg_fond_fees = 1.35 # Average fund fees in contract (percent)
contract_fee = 0.35 # Contract fees (percent)
etf_fee = 1.35 # ETF fees outside of the contract (percent)
steuerfreibetrag = 1000 # Annual tax-free allowance in euros
monthly_fees = [[12 * 5, 28.88], [(60 - 21) * 12, 17.86]] # Monthly fees in euros
regular_tax_rate = 25 # Regular tax rate (percent)
contract_tax_rate = 10 # Contractual tax rate (percent)
reorganize_portfolio_times = 0 # Number of portfolio restructuringsThis project is licensed under the MIT License. Feel free to use and modify.