The Home Development Mutual Fund (HDMF), commonly known as the Pag-IBIG ( Pagtutulungan sa Kinabukasan, Ikaw, Bangko, Industriya at Gobyerno) Fund,^{[lower-alpha 1]} is a government-owned and controlled corporation under the Department of Human Settlements and Urban Development of the Philippines responsible for the administration of the national savings program and affordable shelter financing for Filipinos.

Pag-IBIG Fund was founded by virtue of Presidential Decree No. 1530^[1][2] which was signed by President Ferdinand E. Marcos on June 11, 1978, to answer the national need for savings program and affordable housing financing.^[3] Its original purpose was solely as a provident fund to encourage savings among Filipinos. By March 1979, the fund was administered by the National Home Mortgage Finance Corporation (NHMFC),^[1] a government corporation mandated to increase availability of housing loans to Filipino workers.^[4]

By June, HDMF was implemented by virtue of Executive Order No. 538.^[5] Emily Abinoja, Norma Salud, and Marilou Adea, the vice president of the Shelter Savings Group (SSG), an arm of NHMFC, formed a team to conduct a study of the Central Provident Fund, Singapore's national savings program, with the objective of modeling its fund structure. The team received support from advertising agency J. Romero & Associates that came up with the acronym Pag-IBIG, from actuaries Enrique Zalamea and Leo Tan, from Kapisanan ng mga Brodkaster ng Pilipinas (KBP) that disseminated information about HDMF across the country, from Technology Resource Center that provided computer facilities, and from Development Bank of the Philippines that offered the initial mortgage lending facilities.

When the fund was launched in the midst of martial law, it was opposed by the public and across sectors of society. Its functions were decried as a duplicate to the functions of Social Security System and Government Service Insurance System. The required contribution was described by the labor sector as oppressive, by employers that opposed to any additional contribution in behalf of workers, and by the academe as a representation of injustice of the incumbent Marcos regime.^[1]

On December 14, 1980, Presidential Decree No. 1752 was passed that amended the act creating the Home Development Mutual Fund.^[6] Specifically, the decree contained the following distinct features:

• Establishing HDMF as a fund owned by members, with the government serving as its trustee and guarantor
• Setting the mandatory coverage at 1-3% of contribution of no more than P3,000 per month salary base.

In 2009,^[7] Republic Act No. 9679,^[8] otherwise known as Home Development Mutual Fund Law of 2009,^[9] was passed into law. It expanded coverage requiring mandatory membership of all employees regardless of status, which would include self-employed persons, regardless of trade, business or occupation with an income salary of at least ₱1,000.^[7] It also included overseas Filipino workers and voluntary membership available to all Filipino immigrants, Filipinos naturalized in other countries, and permanent Filipino residents abroad.^[10]

Membership to the fund is exclusive to all Filipino citizens who are or ought to be covered by the Social Security System (SSS), provided that actual membership in the SSS shall not be a condition precedent to the mandatory coverage in the fund. It shall include, but are not limited to:

• A private employee, whether permanent, temporary, or provisional who is not over sixty years old;
• A household helper earning at least ₱1,000 a month. A household helper is any person who renders domestic services exclusively to a household such as a driver, gardener, cook, governess, and other similar occupations;
• A Filipino seafarer upon the signing of the standard contract of employment between the seafarer and the manning agency, which together with the foreign ship owner, acts as the employer;
• A self-employed person regardless of trade, business or occupation, with an income of at least ₱1,000.00 a month and not over sixty years old;
• An expatriate who is not more than sixty years old and is compulsorily covered by the Social Security System (SSS), regardless of citizenship, nature and duration of employment, and the manner by which the compensation is paid. In the absence of an explicit exemption from SSS coverage, the said expatriate, upon assumption of office, shall be covered by the Fund.
• An expatriate shall refer to a citizen of another country who is living and working in the Philippines.
• All employees who are subject to mandatory coverage by the Government Service Insurance System (GSIS), regardless of their status of appointment, including members of the judiciary and constitutional commissions;
• Uniformed members of the Armed Forces of the Philippines, the Bureau of Fire Protection, the Bureau of Jail Management and Penology, and the Philippine National Police;
• Filipinos employed by foreign-based employers, whether they are deployed locally or abroad or a combination thereof.