Treasury Bills Calculator

tbills_calc.py

def calculate_treasury_bill_return():
    """
    Calculates the return on a Treasury bill.
    Fixed tax rate (if applicable), 365 days/year, and specific maturity options.
    """

    # Get inputs from the user
    while True:
        try:
            face_value = float(input("Enter the Face Value (e.g., 5000000): "))
            if face_value <= 0:
                print("Face Value must be positive.")
                continue
            break
        except ValueError:
            print("Invalid input. Please enter a numeric value for Face Value.")

    while True:
        try:
            interest_rate_percent = float(input("Enter the annual Interest Rate (as a percentage, e.g., 5.5): "))
            break
        except ValueError:
            print("Invalid input. Please enter a numeric value for Interest Rate.")

    while True:
        try:
            days_to_maturity = int(input("Enter the Days to Maturity (91, 182, or 364): "))
            if days_to_maturity not in [91, 182, 364]:
                print("Days to Maturity must be 91, 182, or 364.")
                continue
            break
        except ValueError:
            print("Invalid input. Please enter an integer value for Days to Maturity.")

    while True:
        tax_exempt_input = input("Is the investment tax-exempt? (yes/no): ").lower()
        if tax_exempt_input in ('yes', 'no', 'y', 'n'):
            tax_exempt = tax_exempt_input in ('yes', 'y')
            break
        else:
            print("Invalid input. Please enter 'yes' or 'no'.")

    # Fixed values
    days_in_year = 365
    tax_rate = 0.15 if not tax_exempt else 0.0

    # Calculations
    p = 100 * (1 / (1 + (interest_rate_percent / 100) * (days_to_maturity / days_in_year)))
    investment_amount = (face_value / 100) * p
    gross_return = face_value - investment_amount
    withholding_tax = gross_return * tax_rate
    net_return = gross_return - withholding_tax
    total_paid = investment_amount + withholding_tax

    # Output
    print("\n--- Investment Summary ---")
    print(f"Total Investment Amount: Ksh {investment_amount:,.2f}")
    print(f"Price per Ksh 100 (P): Ksh {p:,.2f}")
    print(f"Gross Return: Ksh {gross_return:,.2f}")

    if not tax_exempt:
        print(f"Withholding Tax: Ksh {withholding_tax:,.2f}")
        
    print(f"Net Return: Ksh {net_return:,.2f}")
    print(f"Total amount (Investment + Tax): Ksh {total_paid:,.2f}")

if __name__ == "__main__":
    calculate_treasury_bill_return()