After we raise (or eliminate) the debt limit, we can return government securities to the trust fund in exchange for the IOUs.

FORBES: A Modest Proposal to Avoid Debt Limit Disaster

That same amount will be credited to the Social Security Trust Fund, in the form of Treasury securities.

WHITEHOUSE: Testimony of Jacob Lew

On Saturday, the Wall Street Journal pointed out that the Social Security trust fund includes trillions in securities, representing past surpluses plus interest.

FORBES: A Modest Proposal to Avoid Debt Limit Disaster