What is the official currency of the Kingdom of Bhutan?

The ngultrum has been the currency of Bhutan. It is subdivided into 100 chhertum (called chetrums on coins until 1979). In 1974, the ngultrum was introduced, replacing the Bhutanese rupee at par. The ngultrum retained the peg to the Indian rupee which the Bhutanese rupee had maintained. The ngultrum does not exchange independently with other nations' currencies but is interchangeable with the Indian rupee.

On June 2, 1974, 1, 5 and 10 ngultrum notes were introduced by the Royal Government of Bhutan, followed by 2, 20, 50, and 100 ngultrums in 1978. On August 4, 1982, the Royal Monetary Authority of Bhutan Act was enacted, although the RMA didn't began actual operations until November 1, 1983, and did not issue its own family of notes until 1986. In 2006, the Monetary Authority introduced its latest series of notes, with denominations of 1, 5, 10, 20, 50, 100, 500, and 1000 ngultrum.