5 Pesos

Mountain Province was one of several Philippine civil administrations that issued emergency guerrilla currency after the Japanese occupation cut off access to Commonwealth-issued notes. The Provincial Board had legal authority to authorize local scrip, and these issues were intended to keep civilian commerce functioning in the Cordillera highlands, where Japanese control was thin and contested throughout much of 1942.

The S603 designation places this within the broader Philippine guerrilla currency series — a category notorious for forgeries both contemporary and modern. Provincial issues from Mountain Province are among the harder ones to authenticate, partly because production standards varied and surviving documentation on authorized print runs is sparse.