Gonzaga Sub-Office (GSO) was inaugurated on July 1985 supplying power to the eastern part of the coverage area of CAGELCO II. It manages four towns of Cagayan namely Gonzaga, Sta. Ana, Sta. Teresita, and Buguey which sums up to 84 barangays and a total of 20,886 member-consumers.

Two action centers located at Pattao, Buguey and Tangatan, Sta. Ana helps in the Collection efforts of the sub-office while three substations (Mission Substation, Tangatan Substation, and CEZA Substation) were put up to accommodate the growing load demand at at Sta. Ana, Cagayan.

The sub-office covers two (2) districts – District VI (Buguey & Sta. Teresita) and District IX (Gonzaga & Sta. Ana).