Okay lets take a simplified example which is close to the numbers of say 2006.
Before: Total public debt $10 trillion
Debt held by the Public $6 trillion
Intragovernmental holdings $4 trillion
( which includes SS Trust Fund $2 trillion)
Current Year: Proposed general fund spending $5 trillion
Tax revenues $4.9 trillion
SS cash surplus $100 billion
SS interest @ 5% $100 billion
Unified surplus for the current year +$100 billion ($5.1 trillion - $5 trillion)
Borrowing needs from the public +$0 ($4.9 trillion income tax + $1 billion FICA cash surplus - S5 trillion general fund spending)
Total public debt -$200 trillion ($10 trillion rolled over + $100 billion in Special Treasuries for the cash surplus + $100 billion in Special Treasuries for the interest accrued)
After: Total Public Debt $10.2 trillion
Debt held by the public $6 trillion Total Intragovernmental holdings $4.2 trillion
(which includes SS Trust Fund $2.2 trillion)
In this scenario the General Fund is running a mild deficit of $100 billion totally financed by the cash surplus from FICA. From the perspective of the bond market the budget is balanced with only existing maturing debt needing to be refinanced. On the other hand the Unified Surplus/Deficit scores at +$100 billion because interest is included as revenue even though not financed out of the public markets. Leaving total public debt up +$200 billion.
So it is simple! General Fund in deficit by $100 billion, Unified Budget in surplus by $100 billion, Social Security Trust Fund in surplus by $200 billion, Public Debt in deficit by $200 billion. Net borrowing needs $0.
Balanced cash budget plus Unified Budget and Social Security both in surplus = $200 billion in additional long-term debt. Why is my head throbbing a little bit?