To apply for a Pag-IBIG housing loan, you'll generally need to provide a valid ID, proof of income, and a copy of the contract to sell or title of the property you wish to purchase. Additionally, you may need to submit your Pag-IBIG membership ID or proof of membership. It's best to check directly with Pag-IBIG's official website or contact their customer service for the most accurate and updated document requirements, as these can vary based on your personal circumstances.