you should use python's raw_input() instead of input() like this -

Code:
def main():
  gross_income=int(raw_input("Enter Gross&n
bsp;Income"))

  tax_paid=float(raw_input("Enter Tax 
Paid"))

  number_dependents=int(raw_input("Number o
f Dependents"))

  cost_dependent=number_dependents*750
  income=gross_income-cost_dependent
  taxnet_income=income*0.05
...