My understanding of the Medicare/Social Security "lock box" is that it is all BS. Congress looted all the money a long time ago. All that remains are non-marketable IOU's (essentially pieces of paper saying that one arm of the government owes another.)

Keeping the accounting fiction going hides the true deficit, as Karl points out.

But every penny that isn't paid through payroll taxes into the CMS has to come from treasury issuing new debt. They're hiding some of it until the lockbox runs out.

Somebody can correct me if I'm wrong.