In 1960, the Northern Luzon Division of the then General Auditing Office (GAO) was established in Dagupan City, Pangasinan to supervise the operations of all auditing Offices in the province and chartered cities of Region 1 comprising of Abra, Benguet, Ilocos Sur, Ilocos Norte, La Union, Mountain Province, Pangasinan, and Baguio City and Dagupan City, respectively. The first Division Auditor was Mr. Brigido Martinez. In the span of almost fourteen 14 years from 1960 to 1974, the Northern Luzon Division was headed by seven (7) Division Auditors, namely, Auditors Brigido Martinez, Gavino Ferrer, Mena Caparos, Saturnino Villaranda, Abelardo Santos, Anastacio Quirimit, and Lorenzo Lalatag (all deceased). In conformity to the creation of the Commission on Audit under the 1973 Philippine Constitution, the Northern Luzon Division became COA Regional Office No. 1 in 1975. COA Region 1 had Mr. Alejandro Duzon as Officer-in-Charge in 1975 in its temporary office at the Capitol Building, San Fernando La Union. In 1980, the Regional Office was transferred to a rented building at Barangay Lingsat, San Fernando, La Union, until it had its own building constructed at La Trinidad, Benguet. It was during the term of Director Melchor Pentinio when the construction of the Regional Office at La Trinidad was started and completed by Director Samuel Baluma in 1984. The Regional Office was then transferred from San Fernando, La Union to La Trinidad, Benguet in 1984. When the Cordillera Administrative Region (CAR) was created, COA CAR occupied the first floor and COA Region I was at the second floor of the building. In July 28, 1996, the new COA building at Barangay Sevilla, San Fernando, La Union where COA Region 1 is presently housed was completed and inaugurated by Hon. Chairman Celso Gangan assisted by Commisioners Rogelio Espiritu and Sofronio Ursal.
From 1975, COA Region 1 has been under the stewardship of several Directors, namely, Directors Alejandro Duzon, Melchor Pentinio, Samuel Baluma, Arturo Dadufalsa, Editha dela Cruz, Sofronio Flores, Aristedes Achacoso, Crescencio Sunico, Rafael C. Marquez, Lourdes V. Alejan, Sabiniano G. Cabatuan, Delfin P. Aguilar, Lynn S.F. Sicangco and incumbent Director, Michael R. Bacani with the late Lourdes T. Posadas as the first Assistant Regional Director, followed by several Assistant Regional Director, namely, ARD Cornelio Español, Leila S. Paras, Lito Q. Martin, Gloria Cruz, Evelyn Reyes, Eden Rafanan, Helen M. Cailing, Pelilia C. Veloso, Danilo M. Lagason and OIC, Cecilia G. Ancheta. For a short period of time, Directors Fe Martinez, Amado Butawan, Pepe Matu, Jose Modina and Truman Taup served as Officers in Charge of the Regional Office.
All these years, the men and women of COA Region 1 has remained committed to COAs mandated function to safeguard scarce government resources from losses and wastage and to render efficient and effective auditing services to their clientele.