app ready

app.py

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+import gradio as gr
+from app_logic import estimate_net_salary
+
+# Create the slider for salary input.
+salary_slider = gr.Slider(minimum=80e3, maximum=200e3, label="Gross annual salary")
+
+# Create switch inputs.
+self_employed = gr.Checkbox(label="Self-employed")
+
+# Create text to explain the taxes calculation
+explanation = """
+# Salary estimation factors
+
+### Taxes
+ - Income tax is 42%. A lump sum of 10600 is deducted after applying the tax rate, which accounts to a tax threshold in the calculation of individual taxes.
+ - VAT is 19%. It is only applied to self-employed people.
+ - Additional trade tax rate of 3% is to be paid after opening a business.
+ - Solidarity 1.6% tax rate. It's a German specific tax to help rebuild Germany after WWII.
+  
+### Insurances
+ - Health insurance is 14.6% capped at 993 Euro a month, which would amount to 11916 a year.
+ - Retirement contribution is 18.6% capped at 1311 Euro a month, which would amount to 15735 a year.
+ - Unemployment insurance is 2.4% and capped at 170 Euro a month, 2030 a year.
+  
+### Employment/Self-employment
+ - For self-employed people, the health insurance and retirement are to be paid in full.
+ - For employees the health insurance and retirement are split 50/50 between the employer and the employee.
+
+
+### Conclusion
+
+- Some minor and complex tax deductions were not taken into account. 
+- **Based on the estimations above and my desire to earn around 4000 Euro a month, the projected self-employed salary would be around 160K Euro a year.**
+
+### How do I know the estimation is correct?
+
+The estimation for the case of regular employment was tested against a German salary calculator and the results were very close. The calculator can be found [here](https://www.brutto-netto-rechner.info/gehalt/gross_net_calculator_germany.php). The data it was tested with is the following:
+
+- Gross salary: 100000 Euro
+- Age of the employee: 35
+- Federal state: Berlin
+- Tax category: 1
+- Church tax: No
+- Compulsory health, pension and care unemployment insurance: Yes
+- Health insurance add on: 4 % (not included in the calculation in the app)
+
+"""
+
+# Create output interfaces.
+net_salary = gr.Textbox(label="Estimated net annual salary")
+
+# Define the Gradio interface.
+iface = gr.Interface(
+    fn=estimate_net_salary,
+    inputs=[salary_slider, self_employed],
+    outputs=[net_salary],
+    title="Salary Estimator",
+    description="Adjust the salary, choose if you are self-employed and see the estimated net salary.",
+    article=explanation
+)
+
+# Launch the app.
+iface.launch()

app_logic.py

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+# Income taxes
+INCOME_TAX = 0.42 # income tax rate for salaries above 66760 Euro/year
+INCOME_THRESHOLD = 10600 # used in the calculation of the income tax
+VAT = 0.19 # value-added tax rate for self-employed
+ADD_SP_TAX = 0.03 # additional trade tax rate for self-employed 
+SOL_TAX = 0.05 # solidarity tax rate for self-employed
+
+# Social security contributions
+HEALTH_MAX = 993 # max health insurance contribution (capped at 84600 Euro/year)
+RETIRE_MAX = 1311 # max retirement contribution (capped at 84600 Euro/year)
+UNEMP_MAX= 170 # unemployment contribution rate
+
+
+def estimate_net_salary(salary, self_employed=True):
+    if self_employed:
+        additional_income_tax_cash = salary * (VAT + ADD_SP_TAX)
+        sum_social_security = HEALTH_MAX * 12 + RETIRE_MAX * 12 + UNEMP_MAX * 12
+        income_tax_cash = (salary - sum_social_security) * INCOME_TAX - INCOME_THRESHOLD
+        sol_tax_cash = income_tax_cash * SOL_TAX
+    else:
+        additional_income_tax_cash = 0
+        sum_social_security = (HEALTH_MAX * 12 + RETIRE_MAX * 12 + UNEMP_MAX * 12) / 2 # half paid by the employer
+        income_tax_cash = (salary - sum_social_security) * INCOME_TAX - INCOME_THRESHOLD
+        sol_tax_cash = income_tax_cash * SOL_TAX
+
+    net_salary = salary - income_tax_cash - sol_tax_cash - additional_income_tax_cash - sum_social_security
+    return round(net_salary, 0)

requirements.txt

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+gradio==4.26.0