50 Sen - Hassanal Bolkiah 3rd portrait

Brunei's currency operates under a 1967 Currency Interchangeability Agreement with Singapore, meaning every Bruneian dollar — and by extension every sen — remains legally accepted at par in Singapore and vice versa. This arrangement has held without interruption for over five decades, one of the longest-running bilateral currency agreements of its kind in Southeast Asia. The 2019 refresh of Hassanal Bolkiah's portrait on this denomination was the third such update, reflecting the Sultan's age across a reign that began in 1967 — the same year the interchangeability pact was signed.