This program shows on what day the user will be able to retire.

retirement_date.py

"""This program shows on what day the user will be able to retire."""

from datetime import datetime

from dateutil.relativedelta import relativedelta

def get_dob():
    """Get the user's date of birth."""
    print("Please enter your date of birth (dd.mm.yyyy):")
    dob = ""
    while not dob:
        dob_input = input("\n> ")
        # Try to parse date input.
        try:
            dob = datetime.strptime(dob_input, "%d.%m.%Y")
        except ValueError:
            print("Your input has to be in the format stated above.")
            print("Example: 21.10.1990")
        else:
            # Check whether the user entered a future date.
            if dob > datetime.today():
                print("You can't enter a future day as your date of birth!")
                dob = ""
    return dob

def get_retirement_age():
    """Get the user's retirement age according to Austrian law."""
    print("\nPlease enter your gender (f/m):")
    gender = ""
    while gender.lower() not in ("f", "m") or len(gender) != 1:
        gender = input("\n> ").lower()
    if gender == "f":
        ret_age = 60
    else:
        ret_age = 65
    return ret_age

def main():
    """Calculate and show when the user will be able to retire."""
    dob = get_dob()
    ret_age = get_retirement_age()
    ret_date = dob + relativedelta(years=ret_age)
    # Check whether the user has already reached the age of retirement.
    if ret_date > datetime.today():
        print(f"\nYou can retire on {ret_date.strftime('%A, %d.%m.%Y')}.")
        print(f"That will be your {ret_age}th birthday.")
    else:
        print("\nYou can retire already. Good for you!")

if __name__ == "__main__":
    main()