SS numbers and dates of birth and stopping payments for SS and SSI to all of them and make people file for hearings to try and get their benefits back. Of course drastically reducing the staff means the hearings will take years perhaps. The way they play the game is to schedule a hearing for you and maybe that one is within 6 months. But then as the date comes close they send a notice saying that due to an absence of a hearing examiner, for example they are rescheduling for 90 days hence.
Then you go through the hearing process and they take 6 months to issue a decision. You can expect that first decision to go against you. Then you have the right to appeal that decision. You will be given an appeal date that is about 6 months to a year down the road. Then the scheduling delays will happen again. Then once the appeal hearing takes place you will get a decision perhaps 6 months or more later.
Even though in most cases the facts are simple and straight forward. Such as a birth certificate and a driver's license. In SSI cases they may not accept your doctor's report on its face and they may have you examined by someone. Expect that appointment to be well into the future and the report to take quite awhile also. You can expect their "exam doctor" to disagree with your doctor about degree of disability etc.
So you get to fight through this whole thing all without getting the money you have coming and likely facing financial struggles as a result. Some people may get their hearings and decisions to sail right along but I have known people with plenty of horror stories.