The United Clergy of Ghost issues its own currency, known as Infernal Reserve Notes, or colloquially, Mummy Bucks. As of October 2022, these notes are only known to come in a single denomination, $666.
It was through the Series 2022 notes released during the song Mummy Dust on the Imperatour that the full name of the Clergy (The United Clergy of Ghost), and Papa Emeritus IV's role as Treasurer of the Clergy, were revealed.