Nothing is ever paid back. Worthless IOUs are put in a file cabinet.
From your link:
"The larger question posed by critics of the trust fund system is if and how the government will provide cash for all the bonds, now totaling
$2.8 trillion. These bonds are a special class of
securities unique to the Social Security fund that can’t be sold. Because they’re not-marketable, some contend that they’re "worthless IOUs."
"These special-issue things, they’re all in a
filing cabinet in West Virginia. That’s the entire trust fund," Smith said in an interview. "There’s no trust, and there are no funds."
Prior presidents stole the $2.8T SS surplus and put in worthless IOUs. Now it time to pay the fuck up. I want the cap removed and a 0.50% tax increase to fully fund SS.