This return shall be filed in triplicate by the following individuals regardless of amount of gross income: 1) A resident citizen engaged in trade, business, or practice of profession within and without the Philippines. 2) A resident alien, non-resident citizen or non-resident alien individual engaged in trade, business or practice of profession within the Philippines. 3) A trustee of a trust, guardian of a minor, executor/administrator of an estate, or any person acting in any fiduciary capacity for any person, where such trust, estate, minor, or person is engaged in trade or business.