A few years back a drone at the Philadelphia Fed proposed tagging all currency so it could be made to depreciate over time if it’s not spent. Don’t give the bastards any more ideas.
It's close now with the re-design of the bills. When my mother-in-law passed away in 2008, we discovered a small stash of money in the house that was of the old design. It was divided among the siblings, my wife being one. When she went to spend one of the old-style fifty-dollar bills, she was looked at by the establishment like she was trying to pass a counterfeit bill.