Under the Spanish colonial rule, the Royal Audiencia, a high court, presented its audit reports on the financial condition of the archipelagic colony to the authority. Then, the Tribunal de Cuentas became the highest institution of audit having the exclusive right to conduct audits of all concerning the state finance. With the legal influence from the United States, then an audit agency was set up for the Philippines. Its audit system requires analyzes of all transactions and started to apply the true practices of audit. In 1935, General Auditing Office (GAO) was formed and chaired by an Auditor General whose authority was mandated through the constitution. GAO is responsible to conduct audits of all financial reports, also audit of all expenditures and assets of the government. The GAO was reestablished after the Second World War and changed its name to Commission on Audit (COA) under the 1973 constitution. It is now considered as an important partner of the government in implementing its national development programs and in improving the public welfare of the Philippine people.
The Philippine constitution rules that COA is an independent institution. COA submits its annual reports to the president and congress within the timeframe set by the law. Its reports cover the financial and operational condition of the government, subdivisions, state institutions, and all other organizations concerned.
The constitution rules that COA has the right to conduct audits of all financial reports of the government. The audit targets include income, expenditure, uses of the governmental resources. The COA is responsible to determine regulations on accountancy and audit system. It also has an exclusive authority to determine the coverage and technique of its audit, and bans any regulations that limit the coverage of its audit.