1 Sen - Hassanal Bolkiah 2nd portrait

Brunei's coinage is issued by the Autoriti Monetari Brunei Darussalam, established in 2011 to absorb the functions of the Brunei Currency and Monetary Board — meaning this type spans the institutional transition mid-series. The "2nd portrait" designation tracks a formal effigy update to Sultan Hassanal Bolkiah, the same ruler who has appeared on Brunei coins since 1967, making him one of the longest-reigning monarchs depicted continuously on a circulating national coinage.

Brunei and Singapore maintain a Currency Interchangeability Agreement dating to 1967, under which Brunei dollars and Singapore dollars are accepted at par in both countries.