“It’s Done and Dusted”: Finished with Nothing Left

“It’s done and dusted” means that something has been completely finished or settled, with no remaining steps. Dusted does not literally refer to removing dust. Together, the two words form a fixed expression that adds a sense of finality to the simpler “It’s done”: the loose ends are gone and everyone can move on.

The phrase is natural in Australian and British conversation. American speakers will generally understand it, but use it less often. Its tone is informal and mildly relieved, so it suits completed work, paperwork, arrangements or competitions: “The paperwork’s done and dusted, so we can start on Monday.” Applied to a serious loss or the end of a relationship, it may sound too brisk or dismissive.

https://dictionary.cambridge.org/dictionary/english/be-done-and-dusted
https://www.collinsdictionary.com/dictionary/english/done-and-dusted