There is no rule for how long you need to age a whiskey. However, distillers typically label unaged whiskey as moonshine rather than whiskey. Unaged whiskey will have a clear color, similar to vodka or white rum. The aging process gives whiskey the iconic golden color and its smokey flavor.
In general, distillers age most whiskey for at least three years. However, the longer you age a whiskey, the deeper the flavor and the most expensive it is. Some of the most expensive whiskey bottles age upwards of 30 years.