Retrieves the federal and state-specific default withholding percentages applied to retirement distributions for a given tax year.

These are the rates DriveWealth applies when a distribution request carries no withholding election of its own. This endpoint is a read-only reference lookup — calling it does not create, set, or change a withholding election for any client, and the values returned are not scoped to an individual. To submit an election, set it on the distribution request itself.