This document provides an example computation of income tax for Mr. De Castro, a professor with a monthly salary of 85,000 pesos. It calculates his monthly and annual tax under two scenarios: as a single filer and as married with 4 dependents. As a single filer, Mr. De Castro's tax due is 270,792 pesos resulting in an overpayment of 55,608 pesos. As married with 4 dependents, his tax due is 238,792 pesos resulting in an overpayment of 87,608 pesos.