Liability to pay income-tax: total income of a year is chargeable and taxed at rates in the First Schedule. Liability to pay income-tax arises on a person's total income of the financial year and, where applicable, on other specified periods; tax is charged at rates prescribed in the First Schedule, and is to be collected through deduction or collection at source or paid in advance. Chargeability for a financial year is determined by the Code's provisions as they stand at the commencement of that financial year.