100 Pesos Olive-green back

The Bank of the Philippine Islands was a private commercial institution chartered under Spanish colonial law and retained its position as a note-issuing bank well into the American period — an unusual arrangement that persisted until the Commonwealth era forced a restructuring of Philippine currency authority. Having notes printed by the Bureau of Engraving and Printing in Washington placed the BPI's paper on equal production footing with U.S. federal currency, a point not lost on Filipino business circles who regarded BEP-produced notes as a guarantee of quality that locally printed alternatives could not match.

The "olive-green back" designation distinguishes this from earlier color variants in the series — a deliberate change, not a printing anomaly.