5 Rupiah Overprint

The Riau Islands overprint series was a direct response to rampant cross-border currency arbitrage between Indonesia and Singapore and Malaysia in the early 1960s. Standard Bank Indonesia notes were being exported in bulk by traders exploiting exchange rate differentials, draining the archipelago's domestic money supply. The solution was a regionally restricted currency — identical in design to the mainland issues but overprinted to confine legal tender status to the Riau Islands specifically.

Percetakan Kebayoran, the government printing works in Jakarta, handled the overprinting domestically rather than commissioning a foreign security printer. The Riau series was withdrawn in 1964 after barely a year in circulation, which keeps surviving low-denomination examples like this one genuinely uncommon in any grade.